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| -rw-r--r-- | lib/Exporter.pm | 34 |
1 files changed, 34 insertions, 0 deletions
diff --git a/lib/Exporter.pm b/lib/Exporter.pm index bd55160f87..00010892fa 100644 --- a/lib/Exporter.pm +++ b/lib/Exporter.pm @@ -310,6 +310,40 @@ unchanged but will trigger a warning (with C<-w>) to avoid misspelt tags names being silently added to @EXPORT or @EXPORT_OK. Future versions may make this a fatal error. +=head2 Generating combined tags + +If several symbol categories exist in %EXPORT_TAGS, it's usually +useful to create the utility ":all" to simplify "use" statements. + +The simplest way to do this is: + + %EXPORT_TAGS = (foo => [qw(aa bb cc)], bar => [qw(aa cc dd)]); + + # add all the other ":class" tags to the ":all" class, + # deleting duplicates + { + my %seen; + + push @{$EXPORT_TAGS{all}}, + grep {!$seen{$_}++} @{$EXPORT_TAGS{$_}} foreach keys %EXPORT_TAGS; + } + +CGI.pm creates an ":all" tag which contains some (but not really +all) of its categories. That could be done with one small +change: + + # add some of the other ":class" tags to the ":all" class, + # deleting duplicates + { + my %seen; + + push @{$EXPORT_TAGS{all}}, + grep {!$seen{$_}++} @{$EXPORT_TAGS{$_}} + foreach qw/html2 html3 netscape form cgi internal/; + } + +Note that the tag names in %EXPORT_TAGS don't have the leading ':'. + =head2 C<AUTOLOAD>ed Constants Many modules make use of C<AUTOLOAD>ing for constant subroutines to |