X-Git-Url: http://git.vpit.fr/?a=blobdiff_plain;f=lib%2FScope%2FUpper.pm;h=7553492c3bde6d88189582c33be7c70f34b70a7c;hb=0441a0ad6e426898c4424b48bff13716b5657757;hp=ebe24a1b1dc534754f43af4b1227704e7cff26b7;hpb=514b3cc42d4717ad8c48f61664e18d2fe656857d;p=perl%2Fmodules%2FScope-Upper.git diff --git a/lib/Scope/Upper.pm b/lib/Scope/Upper.pm index ebe24a1..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; @@ -9,13 +11,13 @@ Scope::Upper - Act on upper scopes. =head1 VERSION -Version 0.16 +Version 0.23 =cut our $VERSION; BEGIN { - $VERSION = '0.16'; + $VERSION = '0.23'; } =head1 SYNOPSIS @@ -24,7 +26,10 @@ L, L, L, L and L : package Scope; - use Scope::Upper qw; + use Scope::Upper qw< + reap localize localize_elem localize_delete + :words + >; sub new { my ($class, $name) = @_; @@ -66,22 +71,22 @@ L, L, L, L and L : package UserLand; { - Scope->new("top"); # initializes $UserLand::tag + Scope->new("top"); # initializes $UserLand::tag { Scope->catch; - my $one = 1 + undef; # prints "top: Use of uninitialized value..." + 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..." - } + print $@; # prints "Can't locate Cwd.pm in @INC + } # (@INC contains:) at..." - require Cwd; # loads Cwd.pm + require Cwd; # loads Cwd.pm } - } # prints "top: done" + } # prints "top: done" L and L : @@ -128,6 +133,28 @@ L : 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 This module lets you defer actions I that will take place when the control flow returns into an upper scope. @@ -145,11 +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. +execute a subroutine in the setting of an upper subroutine stack frame with L ; + +=item * + +uniquely identify contexts with L and L. =back @@ -168,11 +203,18 @@ BEGIN { XSLoader::load(__PACKAGE__, $VERSION); } -=head2 C +=head2 C + + reap { ... }; + reap { ... } $context; + &reap($callback, $context); Adds a destructor that calls C<$callback> (in void context) when the upper scope represented by C<$context> ends. -=head2 C +=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 : @@ -222,7 +264,10 @@ Although I believe it shouldn't be a problem as glob slots definedness is pretty =back -=head2 C +=head2 C + + localize_elem $what, $key, $value; + localize_elem $what, $key, $value, $context; Introduces a C or C delayed to the time of first return into the upper scope denoted by C<$context>. Unlike L, C<$what> must be a string and the type of localization is inferred from its sigil. @@ -231,7 +276,10 @@ C<$key> is either an array index or a hash key, depending of which kind of varia 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. -=head2 C +=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<$what> can be: @@ -244,7 +292,7 @@ A glob, in which case C<$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 * @@ -254,9 +302,13 @@ C<$key> is ignored. =back -=head2 C +=head2 C + + unwind; + unwind @values, $context; -Returns C<@values> I the context pointed by C<$context>, i.e. from the subroutine, eval or format at or just above C<$context>, and immediately restart the program flow at this point - thus effectively returning to an upper scope. +Returns C<@values> I the subroutine, eval or format context pointed by or just above C<$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<$context> parameter is optional and defaults to the current context (making the call equivalent to a bare C) ; otherwise it is mandatory. The upper context isn't coerced onto C<@values>, which is hence always evaluated in list context. This means that @@ -270,11 +322,49 @@ This means that will set C<$num> to C<'z'>. You can use L to handle these cases. -=head2 C +=head2 C + + yield; + yield @values, $context; + +Returns C<@values> I the context pointed by or just above C<$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. + +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 C, but for the subroutine/eval/format at or just above C<$context>. +Like for L, you can use the fifth value returned by L to handle context coercion. -The previous example can then be "corrected" : +=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 $num = sub { my @a = ('a' .. 'z'); @@ -284,9 +374,72 @@ The previous example can then be "corrected" : will rightfully set C<$num> to C<26>. -=head2 C +=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<$context> is omitted, it defaults to the current context. + +The returned values are, in order : + +=over 4 + +=item * + +I<(index 0)> : the namespace in use when the context was created ; + +=item * + +I<(index 1)> : the name of the file at the point where the context was created ; + +=item * + +I<(index 2)> : the line number at the point where the context was created ; + +=item * + +I<(index 3)> : the name of the subroutine called for this context, or C if this is not a subroutine context ; + +=item * + +I<(index 4)> : a boolean indicating whether a new instance of C<@_> was set up for this context, or C if this is not a subroutine context ; + +=item * + +I<(index 5)> : the context (in the sense of L) in which the context (in our sense) is executed ; + +=item * + +I<(index 6)> : the contents of the string being compiled for this context, or C if this is not an eval context ; + +=item * + +I<(index 7)> : a boolean indicating whether this eval context was created by C, or C if this is not an eval context ; + +=item * + +I<(index 8)> : the value of the lexical hints in use when the context was created ; + +=item * + +I<(index 9)> : a bit string representing the warnings in use when the context was created ; -Executes the code reference C<$code> 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. +=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 { @@ -302,6 +455,8 @@ The code is executed in the context of the C call, and what it returns 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 : @@ -353,6 +508,78 @@ A simple wrapper lets you mimic the interface of L : 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 =head2 C @@ -365,27 +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<$from> is returned if it is already an eval context ; hence C. @@ -395,11 +635,17 @@ Note that C<$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. @@ -414,13 +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> : @@ -430,36 +676,37 @@ 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 + # $cxt = SCOPE(4), UP SUB UP SUB = UP SUB EVAL = UP CALLER(2) = TOP ... -Where L, L and L point to depending on the C<$cxt>: +Where L, L, L, L and L point to depending on the C<$cxt>: sub { eval { sub { { - unwind @things => $cxt; # or uplevel { ... } $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) + }->(); # $cxt = SCOPE(3) = SUB UP SUB = SUB EVAL = CALLER(2) ... # (*) Note that uplevel() will croak if you pass that scope frame, @@ -467,7 +714,7 @@ Where L, L and L point to depending on the C<$cxt>: =head1 EXPORT -The functions 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 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'>. @@ -482,8 +729,10 @@ our %EXPORT_TAGS = ( funcs => [ qw< reap localize localize_elem localize_delete - unwind want_at + unwind yield leave + want_at context_info uplevel + uid validate_uid > ], words => [ qw ], consts => [ qw ], @@ -520,12 +769,37 @@ However, it's possible to hook the end of the current scope compilation with L to replace an L'd code does not work reliably on perl 5.6 yet. -An exception will be thrown to prevent you from doing so. +Calling C 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 @@ -567,7 +841,7 @@ Thanks to Shawn M. Moore for motivation. =head1 COPYRIGHT & LICENSE -Copyright 2008,2009,2010,2011 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.