diff --git a/lib/calcms/ListenerAccess.pm b/lib/calcms/ListenerAccess.pm
index d109d8d..5951215 100644
--- a/lib/calcms/ListenerAccess.pm
+++ b/lib/calcms/ListenerAccess.pm
@@ -12,7 +12,7 @@ use Apache2::Connection ();
 use Apache2::Const -compile => qw(FORBIDDEN OK);
 
 sub handler {
-    my $r = shift;
+    my ($r) = @_;
 
     my $DAYS = 24 * 60 * 60;
     my $OK = Apache2::Const::OK;
diff --git a/lib/calcms/aggregator.pm b/lib/calcms/aggregator.pm
index 53acc65..20302d8 100644
--- a/lib/calcms/aggregator.pm
+++ b/lib/calcms/aggregator.pm
@@ -14,9 +14,7 @@ use Date::Calc;
 our @EXPORT_OK = qw(get_cache configure_cache put_cache get_list check_params);
 
 sub get_list($$) {
-    my $config  = shift;
-    my $request = shift;
-
+    my ($config, $request) = @_;
     my $params = $request->{params}->{checked};
 
     #customize prefiltered request parameters
@@ -63,10 +61,7 @@ sub get_list($$) {
 }
 
 sub get_menu($$$$) {
-    my $config  = shift;
-    my $request = shift;
-    my $date    = shift;
-    my $results = shift;
+    my ($config, $request, $date, $results) = @_;
 
     my $params = $request->{params}->{checked};
 
@@ -89,9 +84,7 @@ sub get_menu($$$$) {
 }
 
 sub get_calendar($$$) {
-    my $config  = shift;
-    my $request = shift;
-    my $date    = shift;
+    my ($config, $request, $date) = @_;
 
     my $params = $request->{params}->{checked};
 
@@ -114,8 +107,7 @@ sub get_calendar($$$) {
 }
 
 sub get_newest_comments($$) {
-    my $config  = shift;
-    my $request = shift;
+    my ($config, $request) = @_;
 
     my $params = {
         template => 'comments_newest.html',
diff --git a/lib/calcms/audio.pm b/lib/calcms/audio.pm
index 3db95a9..7155f38 100644
--- a/lib/calcms/audio.pm
+++ b/lib/calcms/audio.pm
@@ -3,7 +3,7 @@ use warnings;
 use strict;
 
 sub durationToSeconds($) {
-    my $duration = shift;
+    my ($duration) = @_;
 
     if ( $duration =~ /(\d+):(\d\d):(\d\d).(\d\d)/ ) {
         return $1 * 3600 + $2 * 60 + $3 + $4 / 100;
@@ -12,10 +12,7 @@ sub durationToSeconds($) {
 }
 
 sub formatDuration($$$;$) {
-    my $audioDuration = shift;
-    my $eventDuration = shift;
-    my $value         = shift;
-    my $mouseOver     = shift;
+    my ($audioDuration, $eventDuration, $value, $mouseOver) = @_;
 
     return '' unless $audioDuration;
     return '' unless $eventDuration;
@@ -52,7 +49,8 @@ sub formatDuration($$$;$) {
 }
 
 sub formatChannels($) {
-    my $channels = shift;
+    my ($channels) = @_;
+
     return '' unless $channels;
     my $class = "ok";
     $class = "error" if $channels != 2;
@@ -60,7 +58,8 @@ sub formatChannels($) {
 }
 
 sub formatSamplingRate($) {
-    my $samplingRate = shift;
+    my ($samplingRate) = @_;
+
     return '' unless $samplingRate;
     my $class = "ok";
     $class = "error" if $samplingRate != 44100;
@@ -68,7 +67,8 @@ sub formatSamplingRate($) {
 }
 
 sub formatBitrate($) {
-    my $bitrate = shift;
+    my ($bitrate) = @_;
+
     return '' unless $bitrate;
     my $class = 'ok';
     $class = 'warn'  if $bitrate >= 200;
@@ -77,7 +77,8 @@ sub formatBitrate($) {
 }
 
 sub formatBitrateMode($) {
-    my $mode = shift;
+    my ($mode) = @_;
+
     return '' unless $mode;
     my $class = 'ok';
     $class = 'error' if $mode ne 'CBR';
@@ -85,9 +86,9 @@ sub formatBitrateMode($) {
 }
 
 sub formatLoudness {
-    my $value = shift;
-    my $prefix = shift || '';
-    my $round = shift || '';
+    my ($value, $prefix, $round) = @_;
+    $prefix ||= '';
+    $round ||= '';
     return '' unless $value;
 
     $value = sprintf( "%.1f", $value );
@@ -103,8 +104,7 @@ sub formatLoudness {
 }
 
 sub formatFile{
-    my $file     = shift;
-    my $event_id = shift;
+    my ($file, $event_id) = @_;
 
     return '' unless $file;
 
diff --git a/lib/calcms/audio_recordings.pm b/lib/calcms/audio_recordings.pm
index 58c4dcd..12328f2 100644
--- a/lib/calcms/audio_recordings.pm
+++ b/lib/calcms/audio_recordings.pm
@@ -24,8 +24,7 @@ sub get_columns($) {
 
 # get playout entries
 sub get($$) {
-    my $config    = shift;
-    my $condition = shift;
+    my ($config, $condition) = @_;
 
     my $date_range_include = 0;
     $date_range_include = 1
diff --git a/lib/calcms/calendar.pm b/lib/calcms/calendar.pm
index 73d84c6..0762fd1 100644
--- a/lib/calcms/calendar.pm
+++ b/lib/calcms/calendar.pm
@@ -27,8 +27,7 @@ sub get_cached_or_render($$$) {
 }
 
 sub get($$) {
-    my $config  = shift;
-    my $request = shift;
+    my ($config, $request) = @_;
 
     my $params = $request->{params}->{checked};
     my $language = $config->{date}->{language} || 'en';
@@ -315,8 +314,8 @@ sub get_calendar_weeks($$$) {
 }
 
 sub getWeeksOfMonth($$) {
-    my $thisYear  = shift;
-    my $thisMonth = shift;
+    my ($thisYear, $thisMonth) = @_;
+
     my $thisDay   = 1;
 
     # get weekday of 1st of month
diff --git a/lib/calcms/comments.pm b/lib/calcms/comments.pm
index 5673604..915e56d 100644
--- a/lib/calcms/comments.pm
+++ b/lib/calcms/comments.pm
@@ -70,8 +70,7 @@ sub get_cached_or_render($$$;$) {
 }
 
 sub get($$) {
-    my $config  = shift;
-    my $request = shift;
+    my ($config, $request) = @_;
 
     my $params = $request->{params}->{checked};
     my $dbh = db::connect( $config, $request );
@@ -81,9 +80,7 @@ sub get($$) {
 }
 
 sub get_query($$$) {
-    my $dbh     = shift;
-    my $config  = shift;
-    my $request = shift;
+    my ($dbh, $config, $request) = @_;
 
     my $params = $request->{params}->{checked};
 
@@ -229,9 +226,7 @@ sub render($$$$) {
 
 #check if comment exists already
 sub check ($$$) {
-    my $dbh     = shift;
-    my $config  = shift;
-    my $comment = shift;
+    my ($dbh, $config, $comment) = @_;
 
     my $query = qq{
         select  id
@@ -259,9 +254,7 @@ sub check ($$$) {
 
 #used for insert
 sub get_level($$$) {
-    my $dbh     = shift;
-    my $config  = shift;
-    my $comment = shift;
+    my ($dbh, $config, $comment) = @_;
 
     my $parent_id = $comment->{parent_id};
     return 0 unless defined $parent_id;
@@ -294,9 +287,7 @@ sub get_level($$$) {
 }
 
 sub get_by_event($$$) {
-    my $dbh     = shift;
-    my $config  = shift;
-    my $request = $_[0];
+    my ($dbh, $config, $request) = @_;
 
     my $params = $request->{params}->{checked}->{comment};
 
@@ -336,9 +327,7 @@ sub get_by_event($$$) {
 }
 
 sub get_by_time($$$) {
-    my $dbh     = shift;
-    my $config  = shift;
-    my $comment = shift;
+    my ($dbh, $config, $comment) = @_;
 
     my $where       = '';
     my $bind_values = [];
@@ -375,10 +364,7 @@ sub get_by_time($$$) {
 }
 
 sub get_events($$$$) {
-    my $dbh      = shift;
-    my $config   = shift;
-    my $request  = shift;
-    my $comments = shift;
+    my ($dbh, $config, $request, $comments) = @_;
 
     my $params = $request->{params}->{checked}->{comment};
 
@@ -438,9 +424,7 @@ sub get_events($$$$) {
 }
 
 sub insert ($$$) {
-    my $dbh     = shift;
-    my $config  = shift;
-    my $comment = shift;
+    my ($dbh, $config, $comment) = @_;
 
     $comment->{level} = comments::get_level( $dbh, $config, $comment );
 
@@ -461,9 +445,7 @@ sub insert ($$$) {
 }
 
 sub set_lock_status ($$$) {
-    my $dbh     = shift;
-    my $config  = shift;
-    my $comment = shift;
+    my ($dbh, $config, $comment) = @_;
 
     my $id          = $comment->{id};
     my $lock_status = $comment->{set_lock_status};
@@ -489,9 +471,7 @@ sub set_lock_status ($$$) {
 }
 
 sub set_news_status($$$) {
-    my $dbh     = shift;
-    my $config  = shift;
-    my $comment = shift;
+    my ($dbh, $config, $comment) = @_;
 
     my $id          = $comment->{id};
     my $news_status = $comment->{set_news_status};
@@ -505,9 +485,7 @@ sub set_news_status($$$) {
 }
 
 sub update_comment_count ($$$) {
-    my $dbh     = shift;
-    my $config  = shift;
-    my $comment = shift;
+    my ($dbh, $config, $comment) = @_;
 
     my $query = qq{
         select  count(id) count
@@ -530,9 +508,7 @@ sub update_comment_count ($$$) {
 }
 
 sub sort_childs {
-    my $node         = shift;
-    my $nodes        = shift;
-    my $sorted_nodes = shift;
+    my ($node, $nodes, $sorted_nodes) = @_;
 
     #push node into list of sorted nodes
     push @{$sorted_nodes}, $node;
@@ -549,8 +525,7 @@ sub sort_childs {
 
 #precondition: results are presorted by creation date (by sql)
 sub sort($$) {
-    my $config  = shift;
-    my $results = shift;
+    my ($config, $results) = @_;
 
     #define parent nodes
     my $nodes = {};
@@ -578,8 +553,7 @@ sub sort($$) {
 }
 
 sub check_params ($$) {
-    my $config  = shift;
-    my $params  = shift;
+    my ($config, $params) = @_;
     my $comment = {};
 
     $comment->{event_start} = '';
diff --git a/lib/calcms/config.pm b/lib/calcms/config.pm
index 07ea1bf..a50b9be 100644
--- a/lib/calcms/config.pm
+++ b/lib/calcms/config.pm
@@ -14,7 +14,7 @@ my $config = undef;
 
 
 sub get($) {
-    my $filename = shift;
+    my ($filename) = @_;
     return read_config($filename);
 }
 
@@ -25,7 +25,7 @@ sub getFromScriptLocation() {
 }
 
 sub read_config {
-    my $file = $_[0];
+    my ($file) = @_;
 
     my $vars  = {};
     my @stack = ();
diff --git a/lib/calcms/creole_wiki.pm b/lib/calcms/creole_wiki.pm
index c5f35d7..71fe122 100644
--- a/lib/calcms/creole_wiki.pm
+++ b/lib/calcms/creole_wiki.pm
@@ -13,8 +13,7 @@ our @EXPORT_OK =
 
 #convert creole wiki text to event
 sub extractEventFromWikiText($;$) {
-    my $params = shift;
-    my $event  = shift;
+    my ($params, $event) = @_;
     $event = {} unless defined $event;
 
     my $title           = $params->{title}           || '';
@@ -111,7 +110,7 @@ s/\{\{\s*thumbs\/+(.*?)\s*\|\s*(.*?)\s*\}\}/\[\[$local_media_url\/images\/$1\|\{
 }
 
 sub eventToWikiText($$) {
-    my $event = shift;
+    my ($event) = @_;
     my $local_media_url = $event->{local_media_url} || '';
 
     $event->{program} =~ s/^\s+|\s+$//g;
@@ -163,8 +162,7 @@ s/\[\[.*?\/+media\/+images\/+(.*?)\s*\|.*?\{\{.*?\/+media\/+thumbs\/+(.*?)\s*\|\
 
 #extrace meta tags from comment text
 sub extractMeta ($$) {
-    my $comments = shift;
-    my $meta     = shift;
+    my ($comments, $meta) = @_;
 
     $meta = [] unless defined $meta;
 
@@ -202,7 +200,8 @@ sub extractMeta ($$) {
 
 #remove meta tags from comment text
 sub removeMeta($) {
-    my $comments = shift || '';
+    my ($comments) = @_;
+    $comments ||= '';
 
     my $result = '';
     for my $line ( split( /\n/, $comments ) ) {
@@ -216,7 +215,7 @@ sub removeMeta($) {
 
 #add meta tags to comment text
 sub metaToWiki {
-    my $meta = shift;
+    my ($meta) = @_;
 
     my $result = '';
     for my $pair (@$meta) {
diff --git a/lib/calcms/db.pm b/lib/calcms/db.pm
index f31965c..6d4ee4f 100644
--- a/lib/calcms/db.pm
+++ b/lib/calcms/db.pm
@@ -150,8 +150,7 @@ sub put($$$) {
 
 # deprecated
 sub quote($$) {
-    my $dbh = shift;
-    my $sql = shift;
+    my ($dbh, $sql) = @_;
 
     $sql =~ s/\_/\\\_/g;
     return $dbh->quote($sql);
@@ -159,9 +158,7 @@ sub quote($$) {
 
 #subtract hours, deprecated(!)
 sub shift_date_by_hours($$$) {
-    my $dbh    = shift;
-    my $date   = shift;
-    my $offset = shift;
+    my ($dbh, $date, $offset) = @_;
 
     my $query       = 'select date(? - INTERVAL ? HOUR) date';
     my $bind_values = [ $date, $offset ];
@@ -171,9 +168,7 @@ sub shift_date_by_hours($$$) {
 
 #add minutes, deprecated(!)
 sub shift_datetime_by_minutes($$$) {
-    my $dbh      = shift;
-    my $datetime = shift;
-    my $offset   = shift;
+    my ($dbh, $datetime, $offset) = @_;
 
     my $query       = "select ? + INTERVAL ? MINUTE date";
     my $bind_values = [ $datetime, $offset ];
diff --git a/lib/calcms/event_history.pm b/lib/calcms/event_history.pm
index fec59bb..48fafea 100644
--- a/lib/calcms/event_history.pm
+++ b/lib/calcms/event_history.pm
@@ -113,8 +113,7 @@ sub insert($$) {
 
 # insert event
 sub insert_by_event_id ($$){
-    my $config  = shift;
-    my $options = shift;
+    my ($config, $options) = @_;
 
     return undef unless defined $options->{project_id};
     return undef unless defined $options->{studio_id};
diff --git a/lib/calcms/events.pm b/lib/calcms/events.pm
index d5c0b77..27171c3 100644
--- a/lib/calcms/events.pm
+++ b/lib/calcms/events.pm
@@ -482,11 +482,10 @@ sub add_recurrence_dates {
 }
 
 sub calc_dates {
-    my $config          = shift;
-    my $result          = shift;
-    my $params          = shift || {};
-    my $previous_result = shift || {};
-    my $time_diff       = shift || '';
+    my ($config, $result, $params, $previous_result, $time_diff) = @_;
+    $params          ||= {};
+    $previous_result ||= {};
+    $time_diff       ||= '';
 
     $result->{utc_offset} = $time_diff;
     $result->{time_zone}  = $config->{date}->{time_zone};
@@ -642,8 +641,7 @@ sub set_listen_key{
 
 sub set_upload_status($$){
     my ($config, $event) = @_; 
-                    
-    print STDERR "set upload_status=$event->{upload_status} for ".$event->{event_id}."\n";
+
     return undef unless defined $event->{event_id};
     return undef unless defined $event->{upload_status};
     my $bindValues = [ $event->{upload_status}, $event->{event_id}, $event->{upload_status} ];
@@ -1500,9 +1498,7 @@ sub get_by_image ($$$) {
 # deleting an event is currently disabled
 sub delete ($$$) {
     return;
-    my $request  = shift;
-    my $config   = shift;
-    my $event_id = shift;
+    my ($request, $config, $event_id) = @_;
 
     my $params = $request->{params}->{checked};
     my $dbh = db::connect($config);
@@ -1523,7 +1519,7 @@ sub delete ($$$) {
 
 sub get_duration ($$) {
     my ($config, $event) = @_;
-    
+
     my $timezone = $config->{date}->{time_zone};
     my $start    = time::get_datetime( $event->{start}, $timezone );
     my $end      = time::get_datetime( $event->{end}, $timezone );
diff --git a/lib/calcms/images.pm b/lib/calcms/images.pm
index bb46de1..4df699b 100644
--- a/lib/calcms/images.pm
+++ b/lib/calcms/images.pm
@@ -19,8 +19,7 @@ my $sql_columns = [
 ];
 
 sub get($$) {
-    my $config  = shift;
-    my $options = shift;
+    my ($config, $options) = @_;
 
     my @cond        = ();
     my $bind_values = [];
@@ -99,8 +98,7 @@ sub get($$) {
 }
 
 sub insert_or_update($$) {
-    my $dbh   = shift;
-    my $image = shift;
+    my ($dbh, $image) = @_;
 
     $image->{name} = 'new' if $image->{name} eq '';
     my $entry = get_by_filename( $dbh, $image->{filename} );
@@ -112,8 +110,7 @@ sub insert_or_update($$) {
 }
 
 sub insert ($$) {
-    my $dbh   = shift;
-    my $image = shift;
+    my ($dbh, $image) = @_;
 
     my @sql_columns = @$sql_columns;
 
@@ -154,8 +151,7 @@ sub insert ($$) {
 }
 
 sub update($$) {
-    my $dbh   = shift;
-    my $image = shift;
+    my ($dbh, $image) = @_;
 
     unless ( defined $image->{studio_id} ) {
         print STDERR "missing studio_id at images::update\n";
@@ -213,8 +209,7 @@ sub update($$) {
 }
 
 sub delete($$) {
-    my $dbh   = shift;
-    my $image = shift;
+    my ($dbh, $image) = @_;
 
     unless ( defined $image->{project_id} ) {
         print STDERR "missing project_id at images::delete\n";
@@ -252,11 +247,7 @@ sub delete($$) {
 
 # deactivated
 sub delete_files($$$$$) {
-    my $config          = $_[0];
-    my $local_media_dir = $_[1];
-    my $filename        = $_[2];
-    my $action_result   = $_[3];
-    my $errors          = $_[4];
+    my ($config, $local_media_dir, $filename, $action_result, $errors) = @_;
 
     return undef;
 
@@ -320,8 +311,7 @@ sub delete_file ($$$$) {
 }
 
 sub getPath {
-    my $config  = shift;
-    my $options = shift;
+    my ($config, $options) = @_;
 
     my $dir = $config->{locations}->{local_media_dir};
     return undef unless defined $dir;
@@ -340,8 +330,7 @@ sub getPath {
 }
 
 sub getInternalPath ($$) {
-    my $config  = shift;
-    my $options = shift;
+    my ($config, $options) = @_;
 
     my $dir = $config->{locations}->{local_media_dir};
     return undef unless defined $dir;
@@ -360,14 +349,16 @@ sub getInternalPath ($$) {
 }
 
 sub normalizeName (;$) {
-    my $name = shift;
+    my ($name) = @_;
+
     return undef unless defined $name;
     $name =~ s/.*\///g;
     return $name;
 }
 
 sub readFile($) {
-    my $path    = shift;
+    my ($path) = @_;
+
     my $content = '';
 
     print STDERR "read '$path'\n";
@@ -382,8 +373,7 @@ sub readFile($) {
 }
 
 sub writeFile ($$) {
-    my $path    = shift;
-    my $content = shift;
+    my ($path, $content) = @_;
 
     print STDERR "save '$path'\n";
     open my $fh, '> :raw', $path or return { error => 'could not save image. ' . $! . " $path" };
@@ -394,7 +384,8 @@ sub writeFile ($$) {
 }
 
 sub deleteFile($) {
-    my $path = shift;
+    my ($path) = @_;
+
     return { error => "source '$path' does not exist" } unless -e $path;
 
     #unlink $path;
@@ -403,9 +394,7 @@ sub deleteFile($) {
 }
 
 sub copyFile ($$$) {
-    my $source = shift;
-    my $target = shift;
-    my $errors = shift;
+    my ($source, $target, $errors) = @_;
 
     my $read = images::readFile($source);
     return $read if defined $read->{error};
@@ -415,8 +404,7 @@ sub copyFile ($$$) {
 }
 
 sub publish($$) {
-    my $config   = shift;
-    my $filename = shift;
+    my ($config, $filename) = @_;
 
     print STDERR "publish\n";
     return undef unless defined $config;
@@ -435,8 +423,7 @@ sub publish($$) {
 }
 
 sub depublish ($$) {
-    my $config   = shift;
-    my $filename = shift;
+    my ($config, $filename) = @_;
 
     print STDERR "depublish\n";
     return undef unless defined $config;
@@ -468,8 +455,7 @@ sub checkLicence ($$) {
 }
 
 sub setEventLabels($$) {
-    my $dbh   = shift;
-    my $image = shift;
+    my ($dbh, $image) = @_;
 
     unless ( defined $image->{project_id} ) {
         print STDERR "missing project_id at images::setEventLabels\n";
@@ -495,8 +481,7 @@ sub setEventLabels($$) {
 }
 
 sub setSeriesLabels($$) {
-    my $dbh   = shift;
-    my $image = shift;
+    my ($dbh, $image) = @_;
 
     unless ( defined $image->{project_id} ) {
         print STDERR "missing project_id at images::setSeriesLabels\n";
diff --git a/lib/calcms/localization.pm b/lib/calcms/localization.pm
index 74f277d..760cc5f 100644
--- a/lib/calcms/localization.pm
+++ b/lib/calcms/localization.pm
@@ -17,8 +17,7 @@ our @EXPORT_OK = qw(get getJavascript);
 #    user     : get from user settings
 #    loc      : add to existing localization, optional
 sub get($$) {
-    my $config  = shift;
-    my $options = shift;
+    my ($config, $options) = @_;
 
     #get pot file
     unless ( defined $options->{file} ) {
@@ -63,8 +62,7 @@ sub get($$) {
 }
 
 sub read_po_file($$) {
-    my $po_file = shift;
-    my $loc     = shift;
+    my ($po_file, $loc) = @_;
 
     unless ( -e $po_file ) {
         print STDERR "po file $po_file does not exist\n";
@@ -99,7 +97,7 @@ sub read_po_file($$) {
 }
 
 sub getJavascript ($){
-    my $loc = shift;
+    my ($loc) = @_;
 
     my $out = '<script>';
     $out .= "var loc={};\n";
diff --git a/lib/calcms/log.pm b/lib/calcms/log.pm
index 7f7147f..b4d15f1 100644
--- a/lib/calcms/log.pm
+++ b/lib/calcms/log.pm
@@ -23,7 +23,7 @@ sub error($$) {
 }
 
 sub load_file($) {
-    my $filename = shift;
+    my ($filename) = @_;
 
     my $content = '';
     if ( -e $filename ) {
@@ -36,8 +36,7 @@ sub load_file($) {
 }
 
 sub save_file($$) {
-    my $filename = shift;
-    my $content  = shift;
+    my ($filename, $content) = @_;
 
     #check if directory is writeable
     if ( $filename =~ /^(.+?)\/[^\/]+$/ ) {
@@ -57,8 +56,7 @@ sub save_file($$) {
 }
 
 sub append_file($$) {
-    my $filename = shift;
-    my $content  = shift;
+    my ($filename, $content) = @_;
 
     unless ( ( defined $filename ) && ( $filename ne '' ) && ( -e $filename ) ) {
         print STDERR "cannot append, file '$filename' does not exist\n";
diff --git a/lib/calcms/markup.pm b/lib/calcms/markup.pm
index e5056d8..586c3fe 100644
--- a/lib/calcms/markup.pm
+++ b/lib/calcms/markup.pm
@@ -19,14 +19,14 @@ our @EXPORT_OK =
   qw(fix_line_ends html_to_creole creole_to_html creole_to_plain plain_to_ical ical_to_plain ical_to_xml html_to_plain fix_utf8 uri_encode compress base26);
 
 sub fix_line_ends ($) {
-    my $s = shift;
+    my ($s) = @_;
     $s =~ s/\r?\n|\r/\n/g;
     return $s;
 }
 
 # convert 1..26 to a..z, 27 to aa, inspired by ConvertAA
 sub base26($) {
-    my $num = shift;
+    my ($num) = @_;
     return '' if $num <= 0;
 
     my $s = "";
@@ -39,7 +39,7 @@ sub base26($) {
 }
 
 sub html_to_creole($) {
-    my $s = shift;
+    my ($s) = @_;
 
     #remove elements
     $s =~ s/\<\!\-\-[\s\S]*?\-\-\>//gi;
@@ -153,7 +153,7 @@ sub markdown_to_html($){
 }
 
 sub creole_to_plain($) {
-    my $s = shift;
+    my ($s) = @_;
 
     $s =~ s/\<p\>/\n/gi;
     $s =~ s/\{\{\{((\W+|\w+)+?)\}\}\}/<blockquote>$1<\/blockquote>/g;
@@ -174,7 +174,8 @@ sub creole_to_plain($) {
 }
 
 sub html_to_plain ($) {
-    my $s = shift;
+    my ($s) = @_;
+
     return '' unless defined $s;
     my $tree = HTML::Parse::parse_html( '<body>' . $s . '</body>' );
     my $formatter = HTML::FormatText->new( leftmargin => 0, rightmargin => 2000 );
@@ -381,7 +382,7 @@ my %entity = (
 my $entities = join( '|', keys %entity );
 
 sub encode_xml_element($) {
-    my $text = shift;
+    my ($text) = @_;
 
     my $encoded_text = '';
 
@@ -394,7 +395,7 @@ sub encode_xml_element($) {
 }
 
 sub encode_xml_element_text ($) {
-    my $text = shift;
+    my ($text) = @_;
 
     $text =~ s/&(?!(#[0-9]+|#x[0-9a-fA-F]+|\w+);)/&amp;/g;
     $text =~ s/&($entities);/$entity{$1}/g;
@@ -405,7 +406,8 @@ sub encode_xml_element_text ($) {
 }
 
 sub escapeHtml($) {
-    my $s = shift;
+    my ($s) = @_;
+
     return HTML::Entities::encode_entities( $s, q{&<>"'} );
 }
 
diff --git a/lib/calcms/params.pm b/lib/calcms/params.pm
index 6398fb4..57ba64d 100644
--- a/lib/calcms/params.pm
+++ b/lib/calcms/params.pm
@@ -17,7 +17,7 @@ sub isJson () {
 }
 
 sub get ($) {
-    my $r = shift;
+    my ($r) = @_;
 
     my $tmp_dir      = '/var/tmp/';
     my $upload_limit = 1000 * 1024;
diff --git a/lib/calcms/password_requests.pm b/lib/calcms/password_requests.pm
index 2e2f3ae..d5b8b41 100644
--- a/lib/calcms/password_requests.pm
+++ b/lib/calcms/password_requests.pm
@@ -23,8 +23,7 @@ sub get_columns ($) {
 }
 
 sub get ($$) {
-    my $config    = shift;
-    my $condition = shift;
+    my ($config, $condition) = @_;
 
     my $dbh = db::connect($config);
 
@@ -83,8 +82,7 @@ sub insert ($$) {
 }
 
 sub delete ($$) {
-    my $config    = shift;
-    my $condition = shift;
+    my ($config, $condition) = @_;
 
     my @conditions  = ();
     my @bind_values = ();
@@ -157,9 +155,7 @@ sub sendToken ($$) {
 }
 
 sub changePassword ($$$) {
-    my $config   = shift;
-    my $request  = shift;
-    my $userName = shift;
+    my ($config, $request, $userName) = @_;
 
     my $params      = $request->{params}->{checked};
     my $permissions = $request->{permissions};
@@ -194,7 +190,7 @@ sub changePassword ($$$) {
 }
 
 sub isPasswordInvalid($) {
-    my $password = shift;
+    my ($password) = @_;
     unless ( defined $password || $password eq '' ) {
         return "The password must not be empty.";
     }
diff --git a/lib/calcms/series_dates.pm b/lib/calcms/series_dates.pm
index 8668658..cd64b09 100644
--- a/lib/calcms/series_dates.pm
+++ b/lib/calcms/series_dates.pm
@@ -29,8 +29,7 @@ sub get_columns ($) {
 # get all series_dates for studio_id and series_id within given time range
 # calculate start_date, end_date, weeday, day from start and end(datetime)
 sub get ($;$) {
-    my $config    = shift;
-    my $condition = shift;
+    my ($config, $condition) = @_;
 
     my $dbh = db::connect($config);
 
@@ -107,8 +106,7 @@ sub get ($;$) {
 
 #check if event is scheduled (on permission check)
 sub is_event_scheduled($$) {
-    my $request = shift;
-    my $options = shift;
+    my ($request, $options) = @_;
 
     return 0 unless defined $options->{project_id};
     return 0 unless defined $options->{studio_id};
@@ -131,8 +129,7 @@ sub is_event_scheduled($$) {
 
 #get all series for given studio_id, time range and search
 sub get_series($;$) {
-    my $config    = shift;
-    my $condition = shift;
+    my ($config, $condition) = @_;
 
     my $date_range_include = 0;
     $date_range_include = 1
@@ -251,8 +248,7 @@ sub get_series($;$) {
 }
 
 sub addSeriesScheduleAttributes ($$) {
-    my $config  = shift;
-    my $entries = shift;
+    my ($config, $entries) = @_;
 
     # get series schedule ids used at entries
     my $scheduleIds = { map { $_->{series_schedule_id} => 1 } @$entries };
@@ -360,8 +356,7 @@ sub update($$) {
 }
 
 sub get_schedule_dates($$) {
-    my $schedule = shift;
-    my $options  = shift;
+    my ($schedule, $options) = @_;
 
     my $is_exclude = $options->{exclude} || 0;
     my $dates = [];
@@ -389,13 +384,8 @@ sub get_schedule_dates($$) {
 }
 
 sub get_week_of_month_dates ($$$$$$$) {
-    my $start     = shift;    # datetime string
-    my $end       = shift;    # datetime string
-    my $duration  = shift;    # in minutes
-    my $week      = shift;    # every nth week of month
-    my $weekday   = shift;    # weekday [1..7]
-    my $frequency = shift;    # every 1st,2nd,3th time
-    my $nextDay   = shift;    # add 24 hours to start, (for night hours at last weekday of month)
+    my ($start, $end, $duration, $week, $weekday, $frequency, $nextDay) = @_; 
+    #datetime, datetime, minutes, every nth week of month, weekday [1..7], every 1st,2nd,3th time, add 24 hours to start, (for night hours at last weekday of month)
 
     return undef if $start eq '';
     return undef if $end eq '';
@@ -440,8 +430,7 @@ sub get_week_of_month_dates ($$$$$$$) {
 
 #add duration to a single date
 sub get_single_date ($$) {
-    my $start_datetime = shift;
-    my $duration       = shift;
+    my ($start_datetime, $duration) = @_;
 
     my @start = @{ time::datetime_to_array($start_datetime) };
     return unless @start >= 6;
@@ -460,11 +449,8 @@ sub get_single_date ($$) {
 
 #calculate all dates between start_datetime and end_date with duration(minutes) and frequency(days)
 sub get_dates($$$$) {
-    my $start_datetime = shift;
-    my $end_date       = shift;
-    my $duration       = shift;    # in minutes
-    my $frequency      = shift;    # in days
-         #print "start_datetime:$start_datetime end_date:$end_date duration:$duration frequency:$frequency\n";
+    my ($start_datetime, $end_date, $duration, $frequency) = @_;
+    # in minutes, in days
 
     my @start = @{ time::datetime_to_array($start_datetime) };
     return unless @start >= 6;
@@ -537,8 +523,7 @@ sub delete ($$) {
 
 # get all series dates where no event has been created for
 sub getDatesWithoutEvent ($$) {
-    my $config  = shift;
-    my $options = shift;
+    my ($config, $options) = @_;
 
     return unless defined $options->{project_id};
     return unless defined $options->{studio_id};
diff --git a/lib/calcms/series_schedule.pm b/lib/calcms/series_schedule.pm
index 7ac3883..21ee8c5 100644
--- a/lib/calcms/series_schedule.pm
+++ b/lib/calcms/series_schedule.pm
@@ -30,8 +30,7 @@ sub get_columns ($) {
 
 #map schedule id to id
 sub get($$) {
-    my $config    = shift;
-    my $condition = shift;
+    my ($config, $condition) = @_;
 
     my $dbh = db::connect($config);
 
diff --git a/lib/calcms/studio_timeslot_dates.pm b/lib/calcms/studio_timeslot_dates.pm
index 4657768..6863aef 100644
--- a/lib/calcms/studio_timeslot_dates.pm
+++ b/lib/calcms/studio_timeslot_dates.pm
@@ -25,8 +25,7 @@ sub get_columns ($){
 # get all studio_timeslot_dates for studio_id within given time range
 # calculate start_date, end_date, weeday, day from start and end(datetime)
 sub get ($$){
-    my $config    = shift;
-    my $condition = shift;
+    my ($config, $condition) = @_;
 
     my $date_range_include = 0;
     $date_range_include = 1 if ( defined $condition->{date_range_include} ) && ( $condition->{date_range_include} == 1 );
@@ -171,10 +170,8 @@ sub update {
 # calculate all start/end datetimes between start_date and stop_date with a frequency(days)
 # returns list of hashs with start and end
 sub get_dates {
-    my $start_datetime = shift;    # start
-    my $end_datetime   = shift;    # start
-    my $stop_date      = shift;    # limit recurring events
-    my $frequency      = shift;    # in days
+    my ($start_datetime, $end_datetime, $stop_date, $frequency) = @_;
+                                                    #days
 
     my @start = @{ time::datetime_to_array($start_datetime) };
     return unless @start >= 6;
@@ -284,8 +281,7 @@ sub delete {
 # time based filter to check if studio is assigned to an studio at a given time range
 # return 1 if there is a schedule date starting before start and ending after end
 sub can_studio_edit_events {
-    my $config    = shift;
-    my $condition = shift;
+    my ($config, $condition) = @_;
 
     my @conditions  = ();
     my @bind_values = ();
@@ -348,8 +344,7 @@ sub can_studio_edit_events {
 # returns hashref with start and end of merged slot
 # returns undef if not slot could be found
 sub getMergedDays {
-    my $config    = shift;
-    my $condition = shift;
+    my ($config, $condition) = @_;
 
     my @conditions  = ();
     my @bind_values = ();
diff --git a/lib/calcms/studio_timeslot_schedule.pm b/lib/calcms/studio_timeslot_schedule.pm
index 003ddaf..5d30f86 100644
--- a/lib/calcms/studio_timeslot_schedule.pm
+++ b/lib/calcms/studio_timeslot_schedule.pm
@@ -14,7 +14,7 @@ use studio_timeslot_dates();
 our @EXPORT_OK   = qw(get_columns get insert update delete);
 
 sub get_columns($) {
-	my $config = shift;
+    my ($config) = @_;
 
 	my $dbh = db::connect($config);
 	return db::get_columns_hash( $dbh, 'calcms_studio_timeslot_schedule' );
@@ -22,8 +22,7 @@ sub get_columns($) {
 
 #map schedule id to id
 sub get($$) {
-	my $config    = shift;
-	my $condition = shift;
+    my ($config, $condition) = @_;
 
 	my $dbh = db::connect($config);
 
@@ -62,8 +61,7 @@ sub get($$) {
 }
 
 sub insert($$) {
-	my $config = shift;
-	my $entry  = shift;
+    my ($config, $entry) = @_;
 
 	return unless defined $entry->{project_id};
 	return unless defined $entry->{studio_id};
@@ -77,8 +75,7 @@ sub insert($$) {
 
 #schedule id to id
 sub update($$) {
-	my $config = shift;
-	my $entry  = shift;
+    my ($config, $entry) = @_;
 
 	return unless defined $entry->{project_id};
 	return unless defined $entry->{studio_id};
@@ -112,8 +109,7 @@ sub update($$) {
 
 #map schedule id to id
 sub delete ($$){
-	my $config = shift;
-	my $entry  = shift;
+    my ($config, $entry) = @_;
 
 	return unless defined $entry->{schedule_id};
 
diff --git a/lib/calcms/studios.pm b/lib/calcms/studios.pm
index 32c8837..0ddbaa5 100644
--- a/lib/calcms/studios.pm
+++ b/lib/calcms/studios.pm
@@ -133,8 +133,8 @@ sub check_studio($$) {
 }
 
 sub check ($$) {
-    my $config  = shift;
-    my $options = shift;
+    my ($config, $options) = @_;
+
     return "missing studio_id" unless defined $options->{studio_id};
     return "Please select a studio" if ( $options->{studio_id} eq '-1' );
     return "Please select a studio" if ( $options->{studio_id} eq '' );
diff --git a/lib/calcms/template.pm b/lib/calcms/template.pm
index 14c00e0..ee5eeaa 100644
--- a/lib/calcms/template.pm
+++ b/lib/calcms/template.pm
@@ -120,8 +120,8 @@ sub initTemplate($) {
 sub setRelativeUrls;
 
 sub setRelativeUrls {
-    my $params = shift;
-    my $depth = shift || 0;
+    my ($params, $depth) = @_;
+    $depth ||= 0;
 
     return unless defined $params;
 
@@ -164,10 +164,9 @@ sub setRelativeUrls {
 }
 
 sub check($;$$) {
-    my $config   = shift;
-    my $template = shift || '';
-    my $default  = shift;
+    my ($config, $template, $default) = @_;
 
+    $template ||= '';
     if ( $template =~ /json\-p/ ) {
         $template =~ s/[^a-zA-Z0-9\-\_\.]//g;
         $template =~ s/\.{2,99}/\./g;
diff --git a/lib/calcms/time.pm b/lib/calcms/time.pm
index 60cea17..dfd90b8 100644
--- a/lib/calcms/time.pm
+++ b/lib/calcms/time.pm
@@ -79,28 +79,33 @@ sub getDurations() {
 }
 
 sub getWeekdayNames(;$) {
-    my $language = shift || 'en';
+    my ($language) = @_;
+    $language ||= 'en';
     return $NAMES->{$language}->{weekdays};
 }
 
 sub getWeekdayNamesShort(;$) {
-    my $language = shift || 'en';
+    my ($language) = @_;
+    $language ||= 'en';
     return $NAMES->{$language}->{weekdays_abbr};
 }
 
 sub getMonthNames(;$) {
-    my $language = shift || 'en';
+    my ($language) = @_;
+    $language ||= 'en';
     return $NAMES->{$language}->{months};
 }
 
 sub getMonthNamesShort(;$) {
-    my $language = shift || 'en';
+    my ($language) = @_;
+    $language ||= 'en';
     return $NAMES->{$language}->{months_abbr};
 }
 
 
 sub getWeekdayIndex(;$) {
-    my $weekday = shift || '';
+    my ($weekday) = @_;
+    $weekday ||= '';
     return $WEEKDAY_INDEX->{$weekday};
 }
 
@@ -130,7 +135,7 @@ sub getWeekdays {
 
 #deprecated, for wordpress sync
 sub format_datetime(;$) {
-    my $datetime = shift;
+    my ($datetime) = @_;
     return $datetime if ( $datetime eq '' );
     return add_hours_to_datetime( $datetime, 0 );
 }
@@ -184,40 +189,35 @@ sub datetime_to_rfc822($) {
 
 #get seconds from epoch
 sub datetime_to_utc($$) {
-    my $datetime  = shift;
-    my $time_zone = shift;
+    my ($datetime, $time_zone) = @_;
     $datetime = get_datetime( $datetime, $time_zone );
     return $datetime->epoch();
 }
 
 # get full utc datetime including timezone offset
 sub datetime_to_utc_datetime($$) {
-    my $datetime  = shift;
-    my $time_zone = shift;
+    my ($datetime, $time_zone) = @_;
     $datetime = get_datetime( $datetime, $time_zone );
     return $datetime->format_cldr("yyyy-MM-ddTHH:mm:ssZZZZZ");
 }
 
 #add hours to datetime string
 sub add_hours_to_datetime($;$) {
-    my $datetime = shift;
-    my $hours    = shift;
+    my ($datetime, $hours) = @_;
     $hours = 0 unless defined $hours;
     return time_to_datetime( datetime_to_time($datetime) + ( 3600 * $hours ) );
 }
 
 #add minutes to datetime string
 sub add_minutes_to_datetime($;$) {
-    my $datetime = shift;
-    my $minutes  = shift;
+    my ($datetime, $minutes) = @_;
     $minutes = 0 unless defined $minutes;
     return time_to_datetime( datetime_to_time($datetime) + ( 60 * $minutes ) );
 }
 
 #add days to datetime string
 sub add_days_to_datetime($;$) {
-    my $datetime = shift;
-    my $days     = shift;
+    my ($datetime, $days) = @_;
     $days = 0 unless defined $days;
     my $time = datetime_to_array($datetime);
 
@@ -226,8 +226,7 @@ sub add_days_to_datetime($;$) {
 }
 
 sub add_days_to_date($;$) {
-    my $datetime = shift;
-    my $days     = shift;
+    my ($datetime, $days) = @_;
     $days = 0 unless defined $days;
     my $date = date_to_array($datetime);
     ( $date->[0], $date->[1], $date->[2] ) = Date::Calc::Add_Delta_Days( $date->[0] + 0, $date->[1] + 0, $date->[2] + 0, $days );
@@ -236,7 +235,7 @@ sub add_days_to_date($;$) {
 
 # convert unix time to datetime format
 sub time_to_datetime(;$) {
-    my $time = shift;
+    my ($time) = @_;
     $time = time() unless ( defined $time ) && ( $time ne '' );
     my @t = localtime($time);
     return sprintf( '%04d-%02d-%02d %02d:%02d:%02d', $t[5] + 1900, $t[4] + 1, $t[3], $t[2], $t[1], $t[0] );
@@ -244,7 +243,7 @@ sub time_to_datetime(;$) {
 
 # convert unix time to date format
 sub time_to_date(;$) {
-    my $time = shift;
+    my ($time) = @_;
     $time = time() unless ( defined $time ) && ( $time ne '' );
     my @t = localtime($time);
     return sprintf( '%04d-%02d-%02d', $t[5] + 1900, $t[4] + 1, $t[3] );
@@ -252,7 +251,8 @@ sub time_to_date(;$) {
 
 # convert datetime to a array of date/time values
 sub datetime_to_array(;$) {
-    my $datetime = $_[0] || '';
+    my ($datetime) = @_;
+    $datetime ||= '';
     if ( $datetime =~ /(\d\d\d\d)\-(\d+)\-(\d+)([T\s]+(\d+)\:(\d+)(\:(\d+))?)?/ ) {
         my $year   = $1;
         my $month  = $2;
@@ -279,58 +279,55 @@ sub datetime_to_date(;$) {
 
 #convert datetime array or single value to datetime string
 sub array_to_datetime(;$) {
-    my $date = shift;
+    my ($date, $month, $day, $hour, $minute, $second) = @_;
+
     if ( ref($date) eq 'ARRAY' ) {
         return sprintf( "%04d-%02d-%02d %02d:%02d:%02d", $date->[0], $date->[1], $date->[2], $date->[3], $date->[4], $date->[5] );
     }
-    my $month  = shift;
-    my $day    = shift;
-    my $hour   = shift || '0';
-    my $minute = shift || '0';
-    my $second = shift || '0';
+
+    $hour ||= '0';
+    $minute ||= '0';
+    $second ||= '0';
     return sprintf( "%04d-%02d-%02d %02d:%02d:%02d", $date, $month, $day, $hour, $minute, $second );
 }
 
 #convert date array or single values to date string
 sub array_to_date($;$$) {
-    my $date = shift;
+    my ($date, $month, $day) = @_;
     if ( ref($date) eq 'ARRAY' ) {
         return sprintf( "%04d-%02d-%02d", $date->[0], $date->[1], $date->[2] );
     }
-    my $month = shift;
-    my $day   = shift;
     return sprintf( "%04d-%02d-%02d", $date, $month, $day );
 }
 
 sub array_to_time(;$) {
-    my $date = shift;
+    my ($date, $minute, $second) = @_;
     if ( ref($date) eq 'ARRAY' ) {
         return sprintf( "%02d:%02d:%02d", $date->[3], $date->[4], $date->[5] );
     }
-    my $minute = shift || 0;
-    my $second = shift || 0;
+    $minute ||= '0';
+    $second ||= '0';
     return sprintf( "%02d:%02d:%02d", $date, $minute, $second );
 }
 
 sub array_to_time_hm(;$) {
-    my $date = shift;
+    my ($date, $minute) = @_;
     if ( ref($date) eq 'ARRAY' ) {
         return sprintf( "%02d:%02d", $date->[3], $date->[4] );
     }
-    my $minute = shift || 0;
+    $minute ||= '0';
     return sprintf( "%02d:%02d", $date, $minute );
 }
 
 # get number of days between two days
 sub days_between($$) {
-    my $today      = $_[0];
-    my $date       = $_[1];
+    my ($today, $date) = @_;
     my $delta_days = eval { Date::Calc::Delta_Days( $today->[0], $today->[1], $today->[2], $date->[0], $date->[1], $date->[2] ) };
     return $delta_days;
 }
 
 sub dayOfYear($) {
-    my $datetime = $_[0];
+    my ($datetime) = @_;
     if ( $datetime =~ /(\d\d\d\d)\-(\d+)\-(\d+)/ ) {
         my $year  = $1;
         my $month = $2;
@@ -342,9 +339,7 @@ sub dayOfYear($) {
 
 # get duration in minutes
 sub get_duration($$$) {
-    my $start    = shift;
-    my $end      = shift;
-    my $timezone = shift;
+    my ($start, $end, $timezone) = @_;
     $start = time::get_datetime( $start, $timezone );
     $end   = time::get_datetime( $end,   $timezone );
     my $duration = $end->epoch() - $start->epoch();
@@ -353,9 +348,8 @@ sub get_duration($$$) {
 
 # get duration in seconds
 sub get_duration_seconds($$;$) {
-    my $start    = shift;
-    my $end      = shift;
-    my $timezone = shift || 'UTC';
+    my ($start, $end, $timezone) = @_;
+    $timezone ||= 'UTC';
 
     unless ( defined $start ) {
         print STDERR "time::get_duration_seconds(): start is missing\n";
@@ -395,7 +389,7 @@ sub date_to_array($) {
 # parse date string and return date string
 # pass 'today', return '' on parse error
 sub date_cond($) {
-    my $date = shift;
+    my ($date) = @_;
 
     return '' if ( $date eq '' );
     if ( $date =~ /(\d\d\d\d)\-(\d\d?)\-(\d\d?)/ ) {
@@ -411,7 +405,7 @@ sub date_cond($) {
 #parse time and return time string hh:mm:ss
 #return hh:00 if time is 'now'
 sub time_cond($) {
-    my $time = shift;
+    my ($time) = @_;
 
     return '' if ( $time eq '' );
     if ( $time =~ /(\d\d?)\:(\d\d?)(\:(\d\d))?/ ) {
@@ -432,7 +426,7 @@ sub time_cond($) {
 
 #parse date and time string and return yyyy-mm-ddThh:mm:ss
 sub datetime_cond($) {
-    my $datetime = shift;
+    my ($datetime) = @_;
 
     return '' if ( $datetime eq '' );
     ( my $date, my $time ) = split /[ T]/, $datetime;
@@ -445,7 +439,7 @@ sub datetime_cond($) {
 }
 
 sub check_date($) {
-    my $date = shift;
+    my ($date) = @_;
 
     return "" if ( !defined $date ) || ( $date eq '' );
     if ( $date =~ /(\d\d\d\d)\-(\d\d?)\-(\d\d?)/ ) {
@@ -460,7 +454,7 @@ sub check_date($) {
 }
 
 sub check_time($) {
-    my $time = shift;
+    my ($time) = @_;
     return "" if ( !defined $time ) || ( $time eq '' );
     return $time if ( $time eq 'now' ) || ( $time eq 'future' );
     if ( $time =~ /(\d\d?)\:(\d\d?)/ ) {
@@ -470,7 +464,7 @@ sub check_time($) {
 }
 
 sub check_datetime($) {
-    my $date = shift;
+    my ($date) = @_;
 
     return "" if ( !defined $date ) || ( $date eq '' );
     if ( $date =~ /(\d\d\d\d)\-(\d\d?)\-(\d\d?)[T ](\d\d?)\:(\d\d?)/ ) {
@@ -480,7 +474,7 @@ sub check_datetime($) {
 }
 
 sub check_year_month($) {
-    my $date = shift;
+    my ($date) = @_;
     return -1 unless defined $date;
     return $date if ( $date eq '' );
     if ( $date =~ /(\d\d\d\d)\-(\d\d?)/ ) {
@@ -491,9 +485,8 @@ sub check_year_month($) {
 
 #TODO: remove config dependency
 sub date_time_format($$;$) {
-    my $config   = shift;
-    my $datetime = shift;
-    my $language = shift || $config->{date}->{language} || 'en';
+    my ($config, $datetime, $language) = @_;
+    $language ||= $config->{date}->{language} || 'en';
     if ( defined $datetime && $datetime =~ /(\d\d\d\d)\-(\d\d?)\-(\d\d?)[\sT](\d\d?\:\d\d?)/ ) {
         my $time  = $4;
         my $day   = $3;
@@ -509,9 +502,8 @@ sub date_time_format($$;$) {
 #format datetime to date string
 #TODO: remove config dependency
 sub date_format($$;$) {
-    my $config   = shift;
-    my $datetime = shift;
-    my $language = shift || $config->{date}->{language} || 'en';
+    my ($config, $datetime, $language) = @_;
+    $language ||= $config->{date}->{language} || 'en';
 
     if ( defined $datetime && $datetime =~ /(\d\d\d\d)\-(\d\d?)\-(\d\d?)/ ) {
         my $day   = $3;
@@ -525,7 +517,7 @@ sub date_format($$;$) {
 
 #format datetime to time string
 sub time_format($) {
-    my $datetime = shift;
+    my ($datetime) = @_;
     if ( defined $datetime && $datetime =~ /(\d\d?\:\d\d?)/ ) {
         return $1;
     }
@@ -534,7 +526,7 @@ sub time_format($) {
 
 #get offset from given time_zone
 sub utc_offset($) {
-    my $time_zone = shift;
+    my ($time_zone) = @_;
 
     my $datetime = DateTime->now();
     $datetime->set_time_zone($time_zone);
@@ -571,8 +563,7 @@ sub get_event_date($) {
 
 #get datetime object from datetime string
 sub get_datetime(;$$) {
-    my $datetime = shift;
-    my $timezone = shift;
+    my ($datetime, $timezone) = @_;
 
     return unless defined $datetime;
     return if $datetime eq '';
@@ -599,10 +590,8 @@ sub get_datetime(;$$) {
 
 #get list of nth weekday in month from start to end
 sub get_nth_weekday_in_month(;$$$$) {
-    my $start   = shift;    # datetime string
-    my $end     = shift;    # datetime string
-    my $nth     = shift;    # every nth week of month
-    my $weekday = shift;    # weekday [1..7,'Mo'-'Su','Mo'-'Fr']
+    my ($start, $end, $nth, $weekday) = @_;
+    #datetime, datetime, every nth week of month, weekday [1..7,'Mo'-'Su','Mo'-'Fr']
 
     return [] unless defined $start;
     return [] unless defined $end;
diff --git a/lib/calcms/uac.pm b/lib/calcms/uac.pm
index 713aa47..c4d158c 100644
--- a/lib/calcms/uac.pm
+++ b/lib/calcms/uac.pm
@@ -526,8 +526,7 @@ sub get_role_id ($$) {
 
 # assign a role to an user (for a studio)
 sub assign_user_role($$) {
-    my $config  = shift;
-    my $options = shift;
+    my ($config, $options) = @_;
 
     return undef unless defined $options->{project_id};
     return undef unless defined $options->{studio_id};
@@ -767,8 +766,7 @@ sub setDefaultProject ($$) {
 }
 
 sub setDefaultStudio($$) {
-    my $params       = shift;
-    my $user_presets = shift;
+    my ($params, $user_presets) = @_;
 
     $params->{studio_id} = $user_presets->{studio_id}
       if ( !defined $params->{authAction} ) || ( $params->{authAction} eq '' ) || ( $params->{authAction} eq 'login' );
@@ -802,7 +800,7 @@ sub set_template_permissions ($$) {
 
 #print error message
 sub permissions_denied($) {
-    my $message = shift;
+    my ($message) = @_;
     $message =~ s/_/ /g;
     print '<div class="error">Sorry! Missing permissions to ' . $message . '</div>' . "\n";
     print STDERR 'Sorry! Missing permissions to ' . $message . "\n";
@@ -823,7 +821,7 @@ sub print_warn($) {
 }
 
 sub print_error ($) {
-    my $message = shift;
+    my ($message) = @_;
     print STDERR "ERROR:" . $message . "\n";
     print '<div class="error" head>'
       . '<span class="ui-icon ui-icon-alert" style="float:left"></span>&nbsp;'
diff --git a/lib/calcms/user_day_start.pm b/lib/calcms/user_day_start.pm
index ac6e985..076d375 100644
--- a/lib/calcms/user_day_start.pm
+++ b/lib/calcms/user_day_start.pm
@@ -17,8 +17,7 @@ sub get_columns($) {
 }
 
 sub get ($$) {
-    my $config    = shift;
-    my $condition = shift;
+    my ($config, $condition) = @_;
 
     my @conditions  = ();
     my @bind_values = ();
@@ -49,9 +48,7 @@ sub get ($$) {
 }
 
 sub insert_or_update($$){
-    my $config = shift;
-    my $entry  = shift;
-        print STDERR Dumper $entry;
+    my ($config, $entry) = @_;
     if ( get($config, $entry) ){
         update ($config, $entry);
     } else {
diff --git a/lib/calcms/user_default_studios.pm b/lib/calcms/user_default_studios.pm
index 8a5133a..3ab00ef 100644
--- a/lib/calcms/user_default_studios.pm
+++ b/lib/calcms/user_default_studios.pm
@@ -17,8 +17,7 @@ sub get_columns($) {
 }
 
 sub get ($$) {
-    my $config    = shift;
-    my $condition = shift;
+    my ($config, $condition) = @_;
 
     my @conditions  = ();
     my @bind_values = ();
diff --git a/lib/calcms/user_selected_events.pm b/lib/calcms/user_selected_events.pm
index 7dba5ce..5cf8e65 100644
--- a/lib/calcms/user_selected_events.pm
+++ b/lib/calcms/user_selected_events.pm
@@ -19,8 +19,7 @@ sub get_columns($) {
 }
 
 sub get ($$) {
-    my $config    = shift;
-    my $condition = shift;
+    my ($config, $condition) = @_;
 
     my @conditions  = ();
     my @bind_values = ();
diff --git a/lib/calcms/user_settings.pm b/lib/calcms/user_settings.pm
index 6861224..4852ddc 100644
--- a/lib/calcms/user_settings.pm
+++ b/lib/calcms/user_settings.pm
@@ -66,8 +66,7 @@ our $defaultColors = [
 ];
 
 sub getColors($$) {
-    my $config     = shift;
-    my $conditions = shift;
+    my ($config, $conditions) = @_;
 
     return unless defined $conditions->{user};
     my $user = $conditions->{user};
@@ -101,8 +100,8 @@ sub getColors($$) {
 }
 
 sub getColorCss ($$) {
-    my $config     = shift;
-    my $conditions = shift;
+    my ($config, $conditions) = @_;
+
     return unless defined $conditions->{user};
 
     my $shift = 20;
@@ -139,8 +138,7 @@ sub get_columns($) {
 }
 
 sub get ($$) {
-    my $config    = shift;
-    my $condition = shift;
+    my ($config, $condition) = @_;
 
     my $dbh = db::connect($config);
 
diff --git a/lib/calcms/user_stats.pm b/lib/calcms/user_stats.pm
index 87f5e0a..03f7492 100644
--- a/lib/calcms/user_stats.pm
+++ b/lib/calcms/user_stats.pm
@@ -15,8 +15,7 @@ sub get_columns($) {
 }
 
 sub get ($$) {
-    my $config    = shift;
-    my $condition = shift;
+    my ($config, $condition) = @_;
 
     my $dbh = db::connect($config);
 
@@ -64,8 +63,7 @@ sub get ($$) {
 }
 
 sub get_stats($$) {
-    my $config    = shift;
-    my $condition = shift;
+    my ($config, $condition) = @_;
 
     my $dbh = db::connect($config);
 
@@ -184,9 +182,7 @@ sub update ($$) {
 }
 
 sub increase ($$$) {
-    my $config  = shift;
-    my $usecase = shift;
-    my $options = shift;
+    my ($config, $usecase, $options) = @_;
 
     return undef unless defined $usecase;
     return undef unless defined $options->{project_id};
@@ -219,7 +215,7 @@ sub increase ($$$) {
 }
 
 sub get_active_users{
-    my $config    = shift;
+    my ($config) = @_;
 
     my $dbh = db::connect($config);
 
diff --git a/lib/calcms/work_dates.pm b/lib/calcms/work_dates.pm
index bf289ba..a104bc0 100644
--- a/lib/calcms/work_dates.pm
+++ b/lib/calcms/work_dates.pm
@@ -28,8 +28,7 @@ sub get_columns($) {
 # get all work_dates for studio_id and schedule_id within given time range
 # calculate start_date, end_date, weeday, day from start and end(datetime)
 sub get ($$) {
-    my $config    = shift;
-    my $condition = shift;
+    my ($config, $condition) = @_;
 
     my $date_range_include = 0;
     $date_range_include = 1
@@ -197,8 +196,7 @@ sub update($$) {
 }
 
 sub get_schedule_dates($$) {
-    my $schedule = shift;
-    my $options  = shift;
+    my ($schedule, $options) = @_;
 
     my $is_exclude = $options->{exclude} || 0;
     my $dates = [];
@@ -221,12 +219,8 @@ sub get_schedule_dates($$) {
 }
 
 sub get_week_of_month_dates($$$$$$) {
-    my $start     = shift;    # datetime string
-    my $end       = shift;    # datetime string
-    my $duration  = shift;    # in minutes
-    my $week      = shift;    # every nth week of month
-    my $weekday   = shift;    # weekday [1..7]
-    my $frequency = shift;    # every 1st,2nd,3th time
+    my ($start, $end, $duration, $week, $weekday, $frequency) = @_;
+    # datetime, datetime, minutes, every nth week of month, weekday [1..7], every 1st,2nd,3th time
 
     return undef if $start eq '';
     return undef if $end eq '';
@@ -265,8 +259,7 @@ sub get_week_of_month_dates($$$$$$) {
 
 #add duration to a single date
 sub get_single_date($$) {
-    my $start_datetime = shift;
-    my $duration       = shift;
+    my ($start_datetime, $duration) = @_;
 
     my @start = @{ time::datetime_to_array($start_datetime) };
     return unless @start >= 6;
@@ -285,11 +278,8 @@ sub get_single_date($$) {
 
 #calculate all dates between start_datetime and end_date with duration(minutes) and frequency(days)
 sub get_dates($$$$) {
-    my $start_datetime = shift;
-    my $end_date       = shift;
-    my $duration       = shift;    # in minutes
-    my $frequency      = shift;    # in days
-         #print "start_datetime:$start_datetime end_date:$end_date duration:$duration frequency:$frequency\n";
+    my ($start_datetime, $end_date, $duration, $frequency) = @_;
+    #duration in seconds, frequency in minutes
 
     my @start = @{ time::datetime_to_array($start_datetime) };
     return unless @start >= 6;
diff --git a/lib/calcms/work_schedule.pm b/lib/calcms/work_schedule.pm
index 8296bb0..36132ed 100644
--- a/lib/calcms/work_schedule.pm
+++ b/lib/calcms/work_schedule.pm
@@ -28,8 +28,7 @@ sub get_columns($) {
 
 #map schedule id to id
 sub get($$) {
-    my $config    = shift;
-    my $condition = shift;
+    my ($config, $condition) = @_;
 
     my $dbh = db::connect($config);