From: Perl 5 Porters Date: Thu, 4 Jan 1996 01:02:08 +0000 (+0000) Subject: perl 5.002beta1h patch: lib/Exporter.pm X-Git-Url: http://git.shadowcat.co.uk/gitweb/gitweb.cgi?a=commitdiff_plain;h=2b5b265092e998ff421fee7418b7d4ef196516b8;p=p5sagit%2Fp5-mst-13.2.git perl 5.002beta1h patch: lib/Exporter.pm Include Tim Bunce's enhanced Exporter. I also tried to resolve the two copies of documentation that I had. --- diff --git a/lib/Exporter.pm b/lib/Exporter.pm index 382ee85..de0155b 100644 --- a/lib/Exporter.pm +++ b/lib/Exporter.pm @@ -1,62 +1,5 @@ package Exporter; -=head1 NAME - -Exporter - provide inport/export controls for Perl modules - -=head1 SYNOPSIS - -use Module; -use Module qw(name1 name2 :tag /pattern/ !name); - -=head1 DESCRIPTION - -If the first entry in an import list begins with !, : or / then the -list is treated as a series of specifications which either add to or -delete from the list of names to import. They are processed left to -right. Specifications are in the form: - - [!]name This name only - [!]:DEFAULT All names in @EXPORT - [!]:tag All names in $EXPORT_TAGS{tag} anonymous list - [!]/pattern/ All names in @EXPORT and @EXPORT_OK which match - -A leading ! indicates that matching names should be deleted from the -list of names to import. If the first specification is a deletion it -is treated as though preceded by :DEFAULT. If you just want to import -extra names in addition to the default set you will still need to -include :DEFAULT explicitly. - -e.g., Module.pm defines: - - @EXPORT = qw(A1 A2 A3 A4 A5); - @EXPORT_OK = qw(B1 B2 B3 B4 B5); - %EXPORT_TAGS = (T1 => [qw(A1 A2 B1 B2)], T2 => [qw(A1 A2 B3 B4)]); - - Note that you cannot use tags in @EXPORT or @EXPORT_OK. - Names in EXPORT_TAGS must also appear in @EXPORT or @EXPORT_OK. - -Application says: - - use Module qw(:DEFAULT :T2 !B3 A3); - use Socket qw(!/^[AP]F_/ !SOMAXCONN !SOL_SOCKET); - use POSIX qw(/^S_/ acos asin atan /^E/ !/^EXIT/); - -You can set C<$Exporter::Verbose=1;> to see how the specifications are -being processed and what is actually being imported into modules. - -=head2 Module Version Checking - -The Exporter module will convert an attempt to import a number from a -module into a call to $module_name->require_version($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. - -=cut - require 5.001; $ExportLevel = 0; @@ -69,7 +12,7 @@ sub export { # First make import warnings look like they're coming from the "use". local $SIG{__WARN__} = sub { my $text = shift; - $text =~ s/ at \S*Exporter.pm line \d+.\n//; + $text =~ s/ at \S*Exporter.pm line \d+.*\n//; local $Carp::CarpLevel = 1; # ignore package calling us too. Carp::carp($text); }; @@ -78,55 +21,61 @@ sub export { if $_[0] =~ /^Unable to create sub named "(.*?)::"/; }; - my $pkg = shift; - my $callpkg = shift; - my @imports = @_; - my($type, $sym); - *exports = \@{"${pkg}::EXPORT"}; + my($pkg, $callpkg, @imports) = @_; + my($type, $sym, $oops); + *exports = *{"${pkg}::EXPORT"}; + if (@imports) { - my $oops; - *exports = \%{"${pkg}::EXPORT"}; if (!%exports) { grep(s/^&//, @exports); - @exports{@exports} = (1) x @exports; - foreach $extra (@{"${pkg}::EXPORT_OK"}) { - $exports{$extra} = 1; + @exports{@exports} = (1) x @exports; + my $ok = \@{"${pkg}::EXPORT_OK"}; + if (@$ok) { + grep(s/^&//, @$ok); + @exports{@$ok} = (1) x @$ok; } } if ($imports[0] =~ m#^[/!:]#){ - my(@allexports) = keys %exports; my $tagsref = \%{"${pkg}::EXPORT_TAGS"}; my $tagdata; my %imports; + my($remove, $spec, @names, @allexports); # negated first item implies starting with default set: - unshift(@imports, ':DEFAULT') if $imports[0] =~ m/^!/; - foreach (@imports){ - my(@names); - my($mode,$spec) = m/^(!)?(.*)/; - $mode = '+' unless defined $mode; - - @names = ($spec); # default, maybe overridden below + unshift @imports, ':DEFAULT' if $imports[0] =~ m/^!/; + foreach $spec (@imports){ + $remove = $spec =~ s/^!//; - if ($spec =~ m:^/(.*)/$:){ - my $patn = $1; - @names = grep(/$patn/, @allexports); # XXX anchor by default? - } - elsif ($spec =~ m#^:(.*)# and $tagsref){ - if ($1 eq 'DEFAULT'){ + if ($spec =~ s/^://){ + if ($spec eq 'DEFAULT'){ @names = @exports; } - elsif ($tagsref and $tagdata = $tagsref->{$1}) { + elsif ($tagdata = $tagsref->{$spec}) { @names = @$tagdata; } + else { + warn qq["$spec" is not defined in %${pkg}::EXPORT_TAGS]; + ++$oops; + next; + } + } + elsif ($spec =~ m:^/(.*)/$:){ + my $patn = $1; + @allexports = keys %exports unless @allexports; # only do keys once + @names = grep(/$patn/, @allexports); # not anchored by default } + else { + @names = ($spec); # is a normal symbol name + } + + warn "Import ".($remove ? "del":"add").": @names " + if $Verbose; - warn "Import Mode $mode, Spec $spec, Names @names\n" if $Verbose; - if ($mode eq '!') { - map {delete $imports{$_}} @names; # delete @imports{@names} would be handy :-) + if ($remove) { + foreach $sym (@names) { delete $imports{$sym} } } else { - @imports{@names} = (1) x @names; + @imports{@names} = (1) x @names; } } @imports = keys %imports; @@ -143,44 +92,85 @@ sub export { last; } } elsif ($sym !~ s/^&// || !$exports{$sym}) { - warn qq["$sym" is not exported by the $pkg module ], - "at $callfile line $callline\n"; + warn qq["$sym" is not exported by the $pkg module]; $oops++; - next; } } } - Carp::croak("Can't continue with import errors.\n") if $oops; + Carp::croak("Can't continue after import errors") if $oops; } else { @imports = @exports; } + + *fail = *{"${pkg}::EXPORT_FAIL"}; + if (@fail) { + if (!%fail) { + # Build cache of symbols. Optimise the lookup by adding + # barewords twice... both with and without a leading &. + # (Technique could be applied to %exports cache at cost of memory) + my @expanded = map { /^\w/ ? ($_, '&'.$_) : $_ } @fail; + warn "${pkg}::EXPORT_FAIL cached: @expanded" if $Verbose; + @fail{@expanded} = (1) x @expanded; + } + my @failed; + foreach $sym (@imports) { push(@failed, $sym) if $fail{$sym} } + if (@failed) { + @failed = $pkg->export_fail(@failed); + foreach $sym (@failed) { + warn qq["$sym" is not implemented by the $pkg module ], + "on this architecture"; + } + Carp::croak("Can't continue after import errors") if @failed; + } + } + warn "Importing from $pkg into $callpkg: ", - join(", ",@imports),"\n" if ($Verbose && @imports); + join(", ",sort @imports) if $Verbose; + foreach $sym (@imports) { - $type = '&'; - $type = $1 if $sym =~ s/^(\W)//; + # shortcut for the common case of no type character + (*{"${callpkg}::$sym"} = \&{"${pkg}::$sym"}, next) + unless $sym =~ s/^(\W)//; + $type = $1; *{"${callpkg}::$sym"} = $type eq '&' ? \&{"${pkg}::$sym"} : $type eq '$' ? \${"${pkg}::$sym"} : $type eq '@' ? \@{"${pkg}::$sym"} : $type eq '%' ? \%{"${pkg}::$sym"} : $type eq '*' ? *{"${pkg}::$sym"} : - warn "Can't export symbol: $type$sym\n"; + Carp::croak("Can't export symbol: $type$sym"); } -}; +} sub import { - local ($callpkg, $callfile, $callline) = caller($ExportLevel); my $pkg = shift; + my $callpkg = caller($ExportLevel); export $pkg, $callpkg, @_; } -sub export_tags { - my ($pkg) = caller; - *tags = \%{"${pkg}::EXPORT_TAGS"}; - push(@{"${pkg}::EXPORT"}, - map {$tags{$_} ? @{$tags{$_}} : $_} @_ ? @_ : keys %tags); + +# Utility functions + +sub _push_tags { + my($pkg, $var, $syms) = @_; + my $nontag; + *export_tags = *{"${pkg}::EXPORT_TAGS"}; + push(@{"${pkg}::$var"}, + map { $export_tags{$_} ? @{$export_tags{$_}} : scalar(++$nontag,$_) } + (@$syms) ? @$syms : keys %export_tags); + # This may change to a die one day + Carp::carp("Some names are not tags") if $nontag and $^W; +} + +sub export_tags { _push_tags((caller)[0], "EXPORT", \@_) } +sub export_ok_tags { _push_tags((caller)[0], "EXPORT_OK", \@_) } + + +# Default methods + +sub export_fail { + @_; } sub require_version { @@ -193,3 +183,195 @@ sub require_version { } 1; + +# A simple self test harness. Change 'require Carp' to 'use Carp ()' for testing. +# package main; eval(join('',)) or die $@ unless caller; +__END__ +package Test; +$INC{'Exporter.pm'} = 1; +@ISA = qw(Exporter); +@EXPORT = qw(A1 A2 A3 A4 A5); +@EXPORT_OK = qw(B1 B2 B3 B4 B5); +%EXPORT_TAGS = (T1=>[qw(A1 A2 B1 B2)], T2=>[qw(A1 A2 B3 B4)], T3=>[qw(X3)]); +@EXPORT_FAIL = qw(B4); +Exporter::export_ok_tags('T3', 'unknown_tag'); +sub export_fail { + map { "Test::$_" } @_ # edit symbols just as an example +} + +package main; +$Exporter::Verbose = 1; +#import Test; +#import Test qw(X3); # export ok via export_ok_tags() +#import Test qw(:T1 !A2 /5/ !/3/ B5); +import Test qw(:T2 !B4); +import Test qw(:T2); # should fail +1; + +=head1 NAME + +Exporter - Implements default import method for modules + +=head1 SYNOPSIS + +In module ModuleName.pm: + + package ModuleName; + require Exporter; + @ISA = qw(Exporter); + + @EXPORT = qw(...); # symbols to export by default + @EXPORT_OK = qw(...); # symbols to export on request + %EXPORT_TAGS = tag => [...]; # define names for sets of symbols + +In other files which wish to use ModuleName: + + use ModuleName; # import default symbols into my package + + use ModuleName qw(...); # import listed symbols into my package + + use ModuleName (); # do not import any symbols + +=head1 DESCRIPTION + +The Exporter module implements a default C method which +many modules choose inherit rather than implement their own. + +Perl automatically calls the C method when processing a +C statement for a module. Modules and C are documented +in L and L. Understanding the concept of +modules and how the C statement operates is important to +understanding the Exporter. + +=head2 Selecting What To Export + +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 +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->method) +syntax. By convention you can use a leading underscore on names to +informally indicate that they are 'internal' and not for public use. + +(It is actually possible to get private functions by saying: + + my $subref = sub { ... }; + &$subref; + +But there's no way to call that directly as a method, since a method +must have a name in the symbol table.) + +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. + +Other module design guidelines can be found in L. + +=head2 Specialised Import Lists + +If the first entry in an import list begins with !, : or / then the +list is treated as a series of specifications which either add to or +delete from the list of names to import. They are processed left to +right. Specifications are in the form: + + [!]name This name only + [!]:DEFAULT All names in @EXPORT + [!]:tag All names in $EXPORT_TAGS{tag} anonymous list + [!]/pattern/ All names in @EXPORT and @EXPORT_OK which match + +A leading ! indicates that matching names should be deleted from the +list of names to import. If the first specification is a deletion it +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: + + @EXPORT = qw(A1 A2 A3 A4 A5); + @EXPORT_OK = qw(B1 B2 B3 B4 B5); + %EXPORT_TAGS = (T1 => [qw(A1 A2 B1 B2)], T2 => [qw(A1 A2 B3 B4)]); + + Note that you cannot use tags in @EXPORT or @EXPORT_OK. + Names in EXPORT_TAGS must also appear in @EXPORT or @EXPORT_OK. + +An application using Module can say something like: + + use Module qw(:DEFAULT :T2 !B3 A3); + +Other examples include: + + use Socket qw(!/^[AP]F_/ !SOMAXCONN !SOL_SOCKET); + use POSIX qw(:errno_h :termios_h !TCSADRAIN !/^EXIT/); + +Remember that most patterns (using //) will need to be anchored +with a leading ^, e.g., C rather than C. + +You can say C to see how the +specifications are being processed and what is actually being imported +into modules. + +=head2 Module Version Checking + +The Exporter module will convert an attempt to import a number from a +module into a call to $module_name->require_version($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. + +Since the default require_version method treats the $VERSION number as +a simple numeric value it will regard version 1.10 and being 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. + +=head2 Managing Unknown Symbols + +In some situations you may want to prevent certain symbols from being +exported. Typically this applies to extensions which have functions +or constants that may not exist on some systems. + +The names of any symbols that cannot be exported should be listed +in the C<@EXPORT_FAIL> array. + +If a module attempts to import any of these symbols the Exporter will +will give the module an opportunity to handle the situation before +generating an error. The Exporter will call an export_fail method +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 +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 +simply returns the list unchanged. + +Uses for the export_fail 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 +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: + + %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 +unchanged but will trigger a warning (with -w) to avoid misspelt tags +names being silently added to @EXPORT or @EXPORT_OK. Future versions +may make this a fatal error. + +=cut