X-Git-Url: http://git.shadowcat.co.uk/gitweb/gitweb.cgi?a=blobdiff_plain;f=lib%2FExporter.pm;h=9e1c1ead7f67bcf4a9c7908478296295a4b0f8bb;hb=aaf9c2b26697492a8234a7efe890beef8868ea9b;hp=63534a565d3705433da60fecbd56ae1ba797fbd6;hpb=44ddc0720838c134bcecfee722279a483a169b18;p=p5sagit%2Fp5-mst-13.2.git diff --git a/lib/Exporter.pm b/lib/Exporter.pm index 63534a5..9e1c1ea 100644 --- a/lib/Exporter.pm +++ b/lib/Exporter.pm @@ -9,10 +9,11 @@ require 5.006; our $Debug = 0; our $ExportLevel = 0; our $Verbose ||= 0; -our $VERSION = '5.61'; +our $VERSION = '5.63'; our (%Cache); -# Carp does this now for us, so we can finally live w/o Carp -#$Carp::Internal{Exporter} = 1; + +# Carp 1.05+ does this now for us, but we may be running with an old Carp +$Carp::Internal{Exporter}++; sub as_heavy { require Exporter::Heavy; @@ -102,7 +103,7 @@ Exporter - Implements default import method for modules =head1 SYNOPSIS -In module YourModule.pm: +In module F: package YourModule; require Exporter; @@ -115,9 +116,9 @@ or use Exporter 'import'; # gives you Exporter's import() method directly @EXPORT_OK = qw(munge frobnicate); # symbols to export on request -In other files which wish to use YourModule: +In other files which wish to use C: - use ModuleName qw(frobnicate); # import listed symbols + use YourModule qw(frobnicate); # import listed symbols frobnicate ($left, $right) # calls YourModule::frobnicate Take a look at L for some variants @@ -159,11 +160,11 @@ Do B export method names! Do B export anything else by default without a good reason! Exports pollute the namespace of the module user. If you must export -try to use @EXPORT_OK in preference to @EXPORT and avoid short or +try to use C<@EXPORT_OK> in preference to C<@EXPORT> and avoid short or common symbol names to reduce the risk of name clashes. Generally anything not exported is still accessible from outside the -module using the ModuleName::item_name (or $blessed_ref-Emethod) +module using the C (or C<< $blessed_ref->method >>) syntax. By convention you can use a leading underscore on names to informally indicate that they are 'internal' and not for public use. @@ -178,7 +179,7 @@ how to make inheritance work.) As a general rule, if the module is trying to be object oriented then export nothing. If it's just a collection of functions then -@EXPORT_OK anything but use @EXPORT with caution. For function and +C<@EXPORT_OK> anything but use C<@EXPORT> with caution. For function and method names use barewords in preference to names prefixed with ampersands for the export lists. @@ -191,19 +192,19 @@ them to load your module and import its symbols: =over 4 -=item C +=item C -This imports all the symbols from ModuleName's @EXPORT into the namespace +This imports all the symbols from YourModule's C<@EXPORT> into the namespace of the C statement. -=item C +=item C This causes perl to load your module but does not import any symbols. -=item C +=item C This imports only the symbols listed by the caller into their namespace. -All listed symbols must be in your @EXPORT or @EXPORT_OK, else an error +All listed symbols must be in your C<@EXPORT> or C<@EXPORT_OK>, else an error occurs. The advanced export features of Exporter are accessed like this, but with list entries that are syntactically distinct from symbol names. @@ -232,7 +233,7 @@ is treated as though preceded by :DEFAULT. If you just want to import extra names in addition to the default set you will still need to include :DEFAULT explicitly. -e.g., Module.pm defines: +e.g., F defines: @EXPORT = qw(A1 A2 A3 A4 A5); @EXPORT_OK = qw(B1 B2 B3 B4 B5); @@ -265,9 +266,9 @@ method looks like: MyPackage->export_to_level($where_to_export, $package, @what_to_export); -where $where_to_export is an integer telling how far up the calling stack -to export your symbols, and @what_to_export is an array telling what -symbols *to* export (usually this is @_). The $package argument is +where C<$where_to_export> is an integer telling how far up the calling stack +to export your symbols, and C<@what_to_export> is an array telling what +symbols *to* export (usually this is C<@_>). The C<$package> argument is currently unused. For example, suppose that you have a module, A, which already has an @@ -283,7 +284,7 @@ import function: $A::b = 1; # not a very useful import method } -and you want to Export symbol $A::b back to the module that called +and you want to Export symbol C<$A::b> back to the module that called package A. Since Exporter relies on the import method to work, via inheritance, as it stands Exporter::import() will never get called. Instead, say the following: @@ -306,7 +307,7 @@ Note: Be careful not to modify C<@_> at all before you call export_to_level =head2 Exporting without inheriting from Exporter -By including Exporter in your @ISA you inherit an Exporter's import() method +By including Exporter in your C<@ISA> you inherit an Exporter's import() method but you also inherit several other helper methods which you probably don't want. To avoid this you can do @@ -315,7 +316,7 @@ want. To avoid this you can do which will export Exporter's own import() method into YourModule. Everything will work as before but you won't need to include Exporter in -@YourModule::ISA. +C<@YourModule::ISA>. Note: This feature was introduced in version 5.57 of Exporter, released with perl 5.8.3. @@ -323,14 +324,14 @@ of Exporter, released with perl 5.8.3. =head2 Module Version Checking The Exporter module will convert an attempt to import a number from a -module into a call to $module_name-Erequire_version($value). This can +module into a call to C<< $module_name->require_version($value) >>. This can be used to validate that the version of the module being used is greater than or equal to the required version. -The Exporter module supplies a default require_version method which -checks the value of $VERSION in the exporting module. +The Exporter module supplies a default C method which +checks the value of C<$VERSION> in the exporting module. -Since the default require_version method treats the $VERSION number as +Since the default C method treats the C<$VERSION> number as a simple numeric value it will regard version 1.10 as lower than 1.9. For this reason it is strongly recommended that you use numbers with at least two decimal places, e.g., 1.09. @@ -351,37 +352,37 @@ with a list of the failed symbols: @failed_symbols = $module_name->export_fail(@failed_symbols); -If the export_fail method returns an empty list then no error is +If the C method returns an empty list then no error is recorded and all the requested symbols are exported. If the returned list is not empty then an error is generated for each symbol and the -export fails. The Exporter provides a default export_fail method which +export fails. The Exporter provides a default C method which simply returns the list unchanged. -Uses for the export_fail method include giving better error messages +Uses for the C method include giving better error messages for some symbols and performing lazy architectural checks (put more -symbols into @EXPORT_FAIL by default and then take them out if someone +symbols into C<@EXPORT_FAIL> by default and then take them out if someone actually tries to use them and an expensive check shows that they are usable on that platform). =head2 Tag Handling Utility Functions -Since the symbols listed within %EXPORT_TAGS must also appear in either -@EXPORT or @EXPORT_OK, two utility functions are provided which allow -you to easily add tagged sets of symbols to @EXPORT or @EXPORT_OK: +Since the symbols listed within C<%EXPORT_TAGS> must also appear in either +C<@EXPORT> or C<@EXPORT_OK>, two utility functions are provided which allow +you to easily add tagged sets of symbols to C<@EXPORT> or C<@EXPORT_OK>: %EXPORT_TAGS = (foo => [qw(aa bb cc)], bar => [qw(aa cc dd)]); Exporter::export_tags('foo'); # add aa, bb and cc to @EXPORT Exporter::export_ok_tags('bar'); # add aa, cc and dd to @EXPORT_OK -Any names which are not tags are added to @EXPORT or @EXPORT_OK +Any names which are not tags are added to C<@EXPORT> or C<@EXPORT_OK> unchanged but will trigger a warning (with C<-w>) to avoid misspelt tags -names being silently added to @EXPORT or @EXPORT_OK. Future versions +names being silently added to C<@EXPORT> or C<@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 +If several symbol categories exist in C<%EXPORT_TAGS>, it's usually useful to create the utility ":all" to simplify "use" statements. The simplest way to do this is: @@ -397,7 +398,7 @@ The simplest way to do this is: grep {!$seen{$_}++} @{$EXPORT_TAGS{$_}} foreach keys %EXPORT_TAGS; } -CGI.pm creates an ":all" tag which contains some (but not really +F creates an ":all" tag which contains some (but not really all) of its categories. That could be done with one small change: @@ -411,7 +412,7 @@ change: foreach qw/html2 html3 netscape form cgi internal/; } -Note that the tag names in %EXPORT_TAGS don't have the leading ':'. +Note that the tag names in C<%EXPORT_TAGS> don't have the leading ':'. =head2 Ced Constants @@ -509,9 +510,21 @@ C code to just establish the IS-A relationship. For more details, see the documentation and code of L and L. +Another thorough remedy to that runtime vs. +compile-time trap is to use L, +which is a wrapper of Exporter that allows all +boilerplate code at a single gulp in the +use statement. + + use Exporter::Easy ( + OK => [ qw(munge frobnicate) ], + ); + # @ISA setup is automatic + # all assignments happen at compile time + =head2 What not to Export -You have been warned already in L +You have been warned already in L to not export: =over 4 @@ -569,3 +582,6 @@ This library is free software. You can redistribute it and/or modify it under the same terms as Perl itself. =cut + + +