X-Git-Url: http://git.vpit.fr/?a=blobdiff_plain;f=lib%2FScope%2FUpper.pm;h=7553492c3bde6d88189582c33be7c70f34b70a7c;hb=0441a0ad6e426898c4424b48bff13716b5657757;hp=1d6b4d11a70a002d5396f4d3999df902ae9275c0;hpb=0a7ed27cbdbb90c176fc6be11c48e70776c8df84;p=perl%2Fmodules%2FScope-Upper.git diff --git a/lib/Scope/Upper.pm b/lib/Scope/Upper.pm index 1d6b4d1..7553492 100644 --- a/lib/Scope/Upper.pm +++ b/lib/Scope/Upper.pm @@ -1,5 +1,7 @@ package Scope::Upper; +use 5.006_001; + use strict; use warnings; @@ -9,61 +11,92 @@ Scope::Upper - Act on upper scopes. =head1 VERSION -Version 0.08 +Version 0.23 =cut our $VERSION; BEGIN { - $VERSION = '0.08'; + $VERSION = '0.23'; } =head1 SYNOPSIS - package X; +L, L, L, L and L : + + package Scope; - use Scope::Upper qw/reap localize localize_elem localize_delete :words/; + use Scope::Upper qw< + reap localize localize_elem localize_delete + :words + >; - sub desc { shift->{desc} } + sub new { + my ($class, $name) = @_; - sub set_tag { - my ($desc) = @_; + localize '$tag' => bless({ name => $name }, $class) => UP; - # First localize $x so that it gets destroyed last - localize '$x' => bless({ desc => $desc }, __PACKAGE__) => UP; # one scope up + reap { print Scope->tag->name, ": end\n" } UP; + } - reap sub { - my $pkg = caller; - my $x = do { no strict 'refs'; ${$pkg.'::x'} }; # Get the $x in the scope - print $x->desc . ": done\n"; - } => SCOPE 1; # same as UP here + # Get the tag stored in the caller namespace + sub tag { + my $l = 0; + my $pkg = __PACKAGE__; + $pkg = caller $l++ while $pkg eq __PACKAGE__; + no strict 'refs'; + ${$pkg . '::tag'}; + } + + sub name { shift->{name} } + + # Locally capture warnings and reprint them with the name prefixed + sub catch { localize_elem '%SIG', '__WARN__' => sub { - my $pkg = caller; - my $x = do { no strict 'refs'; ${$pkg.'::x'} }; # Get the $x in the scope - CORE::warn($x->desc . ': ' . join('', @_)); - } => UP CALLER 0; # same as UP here + print Scope->tag->name, ': ', @_; + } => UP; + } - # delete last @ARGV element - localize_delete '@ARGV', -1 => UP SUB HERE; # same as UP here + # Locally clear @INC + sub private { + for (reverse 0 .. $#INC) { + # First UP is the for loop, second is the sub boundary + localize_delete '@INC', $_ => UP UP; + } } - package Y; + ... + + package UserLand; { - X::set_tag('pie'); - # $x is now a X object, and @ARGV has one element less - warn 'what'; # warns "pie: what at ..." - ... - } # "pie: done" is printed + Scope->new("top"); # initializes $UserLand::tag - package Z; + { + Scope->catch; + my $one = 1 + undef; # prints "top: Use of uninitialized value..." + + { + Scope->private; + eval { require Cwd }; + print $@; # prints "Can't locate Cwd.pm in @INC + } # (@INC contains:) at..." + + require Cwd; # loads Cwd.pm + } - use Scope::Upper qw/unwind want_at :words/; + } # prints "top: done" + +L and L : + + package Try; + + use Scope::Upper qw; sub try (&) { my @result = shift->(); - my $cx = SUB UP SUB; + my $cx = SUB UP; # Point to the sub above this one unwind +(want_at($cx) ? @result : scalar @result) => $cx; } @@ -71,13 +104,56 @@ BEGIN { sub zap { try { + my @things = qw; return @things; # returns to try() and then outside zap() # not reached - } + }; # not reached } - my @what = zap(); # @what contains @things + my @stuff = zap(); # @stuff contains qw + my $stuff = zap(); # $stuff contains 3 + +L : + + package Uplevel; + + use Scope::Upper qw; + + sub target { + faker(@_); + } + + sub faker { + uplevel { + my $sub = (caller 0)[3]; + print "$_[0] from $sub()"; + } @_ => CALLER(1); + } + + target('hello'); # "hello from Uplevel::target()" + +L and L : + + use Scope::Upper qw; + + my $uid; + + { + $uid = uid(); + { + if ($uid eq uid(UP)) { # yes + ... + } + if (validate_uid($uid)) { # yes + ... + } + } + } + + if (validate_uid($uid)) { # no + ... + } =head1 DESCRIPTION @@ -96,7 +172,19 @@ localize variables, array/hash values or deletions of elements in higher context =item * -return values immediately to an upper level with L, and know which context was in use then with L. +return values immediately to an upper level with L, L and L ; + +=item * + +gather information about an upper context with L and L ; + +=item * + +execute a subroutine in the setting of an upper subroutine stack frame with L ; + +=item * + +uniquely identify contexts with L and L. =back @@ -115,13 +203,20 @@ BEGIN { XSLoader::load(__PACKAGE__, $VERSION); } -=head2 C +=head2 C -Add a destructor that calls C<$callback> (in void context) when the upper scope represented by C<$context> ends. + reap { ... }; + reap { ... } $context; + &reap($callback, $context); -=head2 C +Adds a destructor that calls C<$callback> (in void context) when the upper scope represented by C<$context> ends. -A C delayed to the time of first return into the upper scope denoted by C<$context>. +=head2 C + + localize $what, $value; + localize $what, $value, $context; + +Introduces a C delayed to the time of first return into the upper scope denoted by C<$context>. C<$what> can be : =over 4 @@ -143,24 +238,50 @@ For example, will set C<$x> to a reference to the string C<'foo'>. Other sigils (C<'@'>, C<'%'>, C<'&'> and C<'*'>) require C<$value> to be a reference of the corresponding type. -When the symbol is given by a string, it is resolved when the actual localization takes place and not when C is called. -This means that +When the symbol is given by a string, it is resolved when the actual localization takes place and not when L is called. +Thus, if the symbol name is not qualified, it will refer to the variable in the package where the localization actually takes place and not in the one where the L call was compiled. +For example, + + { + package Scope; + sub new { localize '$tag', $_[0] => UP } + } - sub tag { localize '$x', $_[0] => UP } + { + package Tool; + { + Scope->new; + ... + } + } + +will localize C<$Tool::tag> and not C<$Scope::tag>. +If you want the other behaviour, you just have to specify C<$what> as a glob or a qualified name. -will localize in the caller's namespace. +Note that if C<$what> is a string denoting a variable that wasn't declared beforehand, the relevant slot will be vivified as needed and won't be deleted from the glob when the localization ends. +This situation never arises with C because it only compiles when the localized variable is already declared. +Although I believe it shouldn't be a problem as glob slots definedness is pretty much an implementation detail, this behaviour may change in the future if proved harmful. =back -=head2 C +=head2 C + + localize_elem $what, $key, $value; + localize_elem $what, $key, $value, $context; -Similar to L but for array and hash elements. -If C<$what> is a glob, the slot to fill is determined from which type of reference C<$value> is ; otherwise it's inferred from the sigil. +Introduces a C or C delayed to the time of first return into the upper scope denoted by C<$context>. +Unlike L, C<$what> must be a string and the type of localization is inferred from its sigil. +The two only valid types are array and hash ; for anything besides those, L will throw an exception. C<$key> is either an array index or a hash key, depending of which kind of variable you localize. -=head2 C +If C<$what> is a string pointing to an undeclared variable, the variable will be vivified as soon as the localization occurs and emptied when it ends, although it will still exist in its glob. -Similiar to L, but for deleting variables or array/hash elements. +=head2 C + + localize_delete $what, $key; + localize_delete $what, $key, $context; + +Introduces the deletion of a variable or an array/hash element delayed to the time of first return into the upper scope denoted by C<$context>. C<$what> can be: =over 4 @@ -171,7 +292,7 @@ A glob, in which case C<$key> is ignored and the call is equivalent to C or C<'%'>, for which the call is equivalent to respectiveley C and C. +A string beginning with C<'@'> or C<'%'>, for which the call is equivalent to respectively C and C. =item * @@ -181,9 +302,13 @@ C<$key> is ignored. =back -=head2 C +=head2 C -Returns C<@values> I the context pointed by C<$context>, i.e. from the subroutine, eval or format just above C<$context>, and immediately restart the program flow at this point - thus effectively returning to (or from, depending on how you see it) an upper context. + unwind; + unwind @values, $context; + +Returns C<@values> I the subroutine, eval or format context pointed by or just above C<$context>, and immediately restarts the program flow at this point - thus effectively returning C<@values> to an upper scope. +If C<@values> is empty, then the C<$context> parameter is optional and defaults to the current context (making the call equivalent to a bare C) ; otherwise it is mandatory. The upper context isn't coerced onto C<@values>, which is hence always evaluated in list context. This means that @@ -197,11 +322,49 @@ This means that will set C<$num> to C<'z'>. You can use L to handle these cases. -=head2 C +=head2 C + + yield; + yield @values, $context; -Like C, but for the subroutine/eval/format just above C<$context>. +Returns C<@values> I the context pointed by or just above C<$context>, and immediately restarts the program flow at this point. +If C<@values> is empty, then the C<$context> parameter is optional and defaults to the current context ; otherwise it is mandatory. -The previous example can then be "corrected" : +L differs from L in that it can target I upper scope (besides a C substitution context) and not necessarily a sub, an eval or a format. +Hence you can use it to return values from a C or a C block : + + my $now = do { + local $@; + eval { require Time::HiRes } or yield time() => HERE; + Time::HiRes::time(); + }; + + my @uniq = map { + yield if $seen{$_}++; # returns the empty list from the block + ... + } @things; + +Like for L, the upper context isn't coerced onto C<@values>. +You can use the fifth value returned by L to handle context coercion. + +=head2 C + + leave; + leave @values; + +Immediately returns C<@values> from the current block, whatever it may be (besides a C substitution context). +C is actually a synonym for C, while C is a synonym for C. + +Like for L, you can use the fifth value returned by L to handle context coercion. + +=head2 C + + my $want = want_at; + my $want = want_at $context; + +Like L, but for the subroutine, eval or format context located at or just above C<$context>. + +It can be used to revise the example showed in L : my $num = sub { my @a = ('a' .. 'z'); @@ -209,7 +372,213 @@ The previous example can then be "corrected" : # not reached }->(); -will righteously set C<$num> to C<26>. +will rightfully set C<$num> to C<26>. + +=head2 C + + my ($package, $filename, $line, $subroutine, $hasargs, + $wantarray, $evaltext, $is_require, $hints, $bitmask, + $hinthash) = context_info $context; + +Gives information about the context denoted by C<$context>, akin to what L provides but not limited only to subroutine, eval and format contexts. +When C<$context> is omitted, it defaults to the current context. + +The returned values are, in order : + +=over 4 + +=item * + +I<(index 0)> : the namespace in use when the context was created ; + +=item * + +I<(index 1)> : the name of the file at the point where the context was created ; + +=item * + +I<(index 2)> : the line number at the point where the context was created ; + +=item * + +I<(index 3)> : the name of the subroutine called for this context, or C if this is not a subroutine context ; + +=item * + +I<(index 4)> : a boolean indicating whether a new instance of C<@_> was set up for this context, or C if this is not a subroutine context ; + +=item * + +I<(index 5)> : the context (in the sense of L) in which the context (in our sense) is executed ; + +=item * + +I<(index 6)> : the contents of the string being compiled for this context, or C if this is not an eval context ; + +=item * + +I<(index 7)> : a boolean indicating whether this eval context was created by C, or C if this is not an eval context ; + +=item * + +I<(index 8)> : the value of the lexical hints in use when the context was created ; + +=item * + +I<(index 9)> : a bit string representing the warnings in use when the context was created ; + +=item * + +I<(index 10)> : a reference to the lexical hints hash in use when the context was created (only on perl 5.10 or greater). + +=back + +=head2 C + + my @ret = uplevel { ...; return @ret }; + my @ret = uplevel { my @args = @_; ...; return @ret } @args, $context; + my @ret = &uplevel($callback, @args, $context); + +Executes the code reference C<$callback> with arguments C<@args> as if it were located at the subroutine stack frame pointed by C<$context>, effectively fooling C and C into believing that the call actually happened higher in the stack. +The code is executed in the context of the C call, and what it returns is returned as-is by C. + + sub target { + faker(@_); + } + + sub faker { + uplevel { + map { 1 / $_ } @_; + } @_ => CALLER(1); + } + + my @inverses = target(1, 2, 4); # @inverses contains (0, 0.5, 0.25) + my $count = target(1, 2, 4); # $count is 3 + +Note that if C<@args> is empty, then the C<$context> parameter is optional and defaults to the current context ; otherwise it is mandatory. + +L also implements a pure-Perl version of C. +Both are identical, with the following caveats : + +=over 4 + +=item * + +The L implementation of C may execute a code reference in the context of B upper stack frame. +The L version can only uplevel to a B stack frame, and will croak if you try to target an C or a format. + +=item * + +Exceptions thrown from the code called by this version of C will not be caught by C blocks between the target frame and the uplevel call, while they will for L's version. +This means that : + + eval { + sub { + local $@; + eval { + sub { + uplevel { die 'wut' } CALLER(2); # for Scope::Upper + # uplevel(3, sub { die 'wut' }) # for Sub::Uplevel + }->(); + }; + print "inner block: $@"; + $@ and exit; + }->(); + }; + print "outer block: $@"; + +will print "inner block: wut..." with L and "outer block: wut..." with L. + +=item * + +L globally overrides the Perl keyword C, while L does not. + +=back + +A simple wrapper lets you mimic the interface of L : + + use Scope::Upper; + + sub uplevel { + my $frame = shift; + my $code = shift; + my $cxt = Scope::Upper::CALLER($frame); + &Scope::Upper::uplevel($code => @_ => $cxt); + } + +Albeit the three exceptions listed above, it passes all the tests of L. + +=head2 C + + my $uid = uid; + my $uid = uid $context; + +Returns an unique identifier (UID) for the context (or dynamic scope) pointed by C<$context>, or for the current context if C<$context> is omitted. +This UID will only be valid for the life time of the context it represents, and another UID will be generated next time the same scope is executed. + + my $uid; + + { + $uid = uid; + if ($uid eq uid()) { # yes, this is the same context + ... + } + { + if ($uid eq uid()) { # no, we are one scope below + ... + } + if ($uid eq uid(UP)) { # yes, UP points to the same scope as $uid + ... + } + } + } + + # $uid is now invalid + + { + if ($uid eq uid()) { # no, this is another block + ... + } + } + +For example, each loop iteration gets its own UID : + + my %uids; + + for (1 .. 5) { + my $uid = uid; + $uids{$uid} = $_; + } + + # %uids has 5 entries + +The UIDs are not guaranteed to be numbers, so you must use the C operator to compare them. + +To check whether a given UID is valid, you can use the L function. + +=head2 C + + my $is_valid = validate_uid $uid; + +Returns true if and only if C<$uid> is the UID of a currently valid context (that is, it designates a scope that is higher than the current one in the call stack). + + my $uid; + + { + $uid = uid(); + if (validate_uid($uid)) { # yes + ... + } + { + if (validate_uid($uid)) { # yes + ... + } + } + } + + if (validate_uid($uid)) { # no + ... + } =head1 CONSTANTS @@ -223,27 +592,40 @@ True iff the module could have been built when thread-safety features. =head3 C + my $top_context = TOP; + Returns the context that currently represents the highest scope. =head3 C + my $current_context = HERE; + The context of the current scope. =head2 Getting a context from a context For any of those functions, C<$from> is expected to be a context. -When omitted, it defaults to the the current context. +When omitted, it defaults to the current context. + +=head3 C -=head3 C + my $upper_context = UP; + my $upper_context = UP $from; The context of the scope just above C<$from>. -=head3 C +=head3 C + + my $sub_context = SUB; + my $sub_context = SUB $from; The context of the closest subroutine above C<$from>. Note that C<$from> is returned if it is already a subroutine context ; hence C. -=head3 C +=head3 C + + my $eval_context = EVAL; + my $eval_context = EVAL $from; The context of the closest eval above C<$from>. Note that C<$from> is returned if it is already an eval context ; hence C. @@ -253,11 +635,17 @@ Note that C<$from> is returned if it is already an eval context ; hence C should denote a number of scopes above the current one. When omitted, it defaults to C<0> and those functions return the same context as L. -=head3 C +=head3 C + + my $context = SCOPE; + my $context = SCOPE $level; The C<$level>-th upper context, regardless of its type. -=head3 C +=head3 C + + my $context = CALLER; + my $context = CALLER $level; The context of the C<$level>-th upper subroutine/eval/format. It kind of corresponds to the context represented by C, but while e.g. C refers to the caller context, C will refer to the top scope in the current context. @@ -272,13 +660,13 @@ Where L fires depending on the C<$cxt> : { reap \&cleanup => $cxt; ... - } # $cxt = SCOPE(0), or HERE + } # $cxt = SCOPE(0) = HERE ... - }->(); # $cxt = SCOPE(1), or UP, or SUB, or CALLER, or CALLER(0) + }->(); # $cxt = SCOPE(1) = UP = SUB = CALLER(0) ... - }; # $cxt = SCOPE(2), or UP UP, or UP SUB, or EVAL, or CALLER(1) + }; # $cxt = SCOPE(2) = UP UP = UP SUB = EVAL = CALLER(1) ... - }->(); # $cxt = SCOPE(3), or SUB UP SUB, or SUB EVAL, or CALLER(2) + }->(); # $cxt = SCOPE(3) = SUB UP SUB = SUB EVAL = CALLER(2) ... Where L, L and L act depending on the C<$cxt> : @@ -288,41 +676,45 @@ Where L, L and L act depending on t sub { { localize '$x' => 1 => $cxt; - # $cxt = SCOPE(0), or HERE + # $cxt = SCOPE(0) = HERE ... } - # $cxt = SCOPE(1), or UP, or SUB, or CALLER, or CALLER(0) + # $cxt = SCOPE(1) = UP = SUB = CALLER(0) ... }->(); - # $cxt = SCOPE(2), or UP UP, or UP SUB, or EVAL, or CALLER(1) + # $cxt = SCOPE(2) = UP UP = UP SUB = EVAL = CALLER(1) ... }; - # $cxt = SCOPE(3), or SUB UP SUB, or SUB EVAL, or CALLER(2) + # $cxt = SCOPE(3) = SUB UP SUB = SUB EVAL = CALLER(2) ... }->(); - # $cxt = SCOPE(4), UP SUB UP SUB, or UP SUB EVAL, or UP CALLER(2), or TOP + # $cxt = SCOPE(4), UP SUB UP SUB = UP SUB EVAL = UP CALLER(2) = TOP ... -Where L and L point to depending on the C<$cxt>: +Where L, L, L, L and L point to depending on the C<$cxt>: sub { eval { sub { { - unwind @things => $cxt; + unwind @things => $cxt; # or yield @things => $cxt + # or uplevel { ... } $cxt ... } ... - }->(); # $cxt = SCOPE(0 .. 1), or HERE, or UP, or SUB, or CALLER(0) + }->(); # $cxt = SCOPE(0) = SCOPE(1) = HERE = UP = SUB = CALLER(0) ... - }; # $cxt = SCOPE(2), or UP UP, or UP SUB, or EVAL, or CALLER(1) + }; # $cxt = SCOPE(2) = UP UP = UP SUB = EVAL = CALLER(1) (*) ... - }->(); # $cxt = SCOPE(3), or SUB UP SUB, or SUB EVAL, or CALLER(2) + }->(); # $cxt = SCOPE(3) = SUB UP SUB = SUB EVAL = CALLER(2) ... + # (*) Note that uplevel() will croak if you pass that scope frame, + # because it cannot target eval scopes. + =head1 EXPORT -The functions L, L, L, L, L and L are only exported on request, either individually or by the tags C<':funcs'> and C<':all'>. +The functions L, L, L, L, L, L, L, L, L and L are only exported on request, either individually or by the tags C<':funcs'> and C<':all'>. The constant L is also only exported on request, individually or by the tags C<':consts'> and C<':all'>. @@ -330,13 +722,20 @@ Same goes for the words L, L, L, L, L, L =cut -use base qw/Exporter/; +use base qw; our @EXPORT = (); our %EXPORT_TAGS = ( - funcs => [ qw/reap localize localize_elem localize_delete unwind want_at/ ], - words => [ qw/TOP HERE UP SUB EVAL SCOPE CALLER/ ], - consts => [ qw/SU_THREADSAFE/ ], + funcs => [ qw< + reap + localize localize_elem localize_delete + unwind yield leave + want_at context_info + uplevel + uid validate_uid + > ], + words => [ qw ], + consts => [ qw ], ); our @EXPORT_OK = map { @$_ } values %EXPORT_TAGS; $EXPORT_TAGS{'all'} = [ @EXPORT_OK ]; @@ -370,14 +769,51 @@ However, it's possible to hook the end of the current scope compilation with L to replace an L'd code frame does not work : + +=over 4 + +=item * + +for a C older than the 5.8 series ; + +=item * + +for a C C run with debugging flags set (as in C) ; + +=item * + +when the runloop callback is replaced by another module. + +=back + +In those three cases, L will look for a C statement in its callback and, if there is one, throw an exception before executing the code. + +Moreover, in order to handle C statements properly, L currently has to suffer a run-time overhead proportional to the size of the callback in every case (with a small ratio), and proportional to the size of B the code executed as the result of the L call (including subroutine calls inside the callback) when a C statement is found in the L callback. +Despite this shortcoming, this XS version of L should still run way faster than the pure-Perl version from L. + =head1 DEPENDENCIES -L (standard since perl 5.006). +L 5.6.1. + +A C compiler. +This module may happen to build with a C++ compiler as well, but don't rely on it, as no guarantee is made in this regard. + +L (core since perl 5.6.0). =head1 SEE ALSO +L, L. + L, L, L, L. +L. + +L is a thin wrapper around L that gives you a continuation passing style interface to L. +It's easier to use, but it requires you to have control over the scope where you want to return. + +L. + =head1 AUTHOR Vincent Pit, C<< >>, L. @@ -386,7 +822,8 @@ You can contact me by mail or on C (vincent). =head1 BUGS -Please report any bugs or feature requests to C, or through the web interface at L. I will be notified, and then you'll automatically be notified of progress on your bug as I make changes. +Please report any bugs or feature requests to C, or through the web interface at L. +I will be notified, and then you'll automatically be notified of progress on your bug as I make changes. =head1 SUPPORT @@ -404,7 +841,7 @@ Thanks to Shawn M. Moore for motivation. =head1 COPYRIGHT & LICENSE -Copyright 2008-2009 Vincent Pit, all rights reserved. +Copyright 2008,2009,2010,2011,2012,2013 Vincent Pit, all rights reserved. This program is free software; you can redistribute it and/or modify it under the same terms as Perl itself.