X-Git-Url: http://git.vpit.fr/?a=blobdiff_plain;f=lib%2FScope%2FUpper.pm;h=b5936dbfa325253e1d2625c83205d71055c33cb7;hb=70187dc24bb0f90a81f58ff2bd52ba7d9c3ac06f;hp=920274050044846fa7f46002fbd66c40e290fddc;hpb=463fb6b2306558e10e95198da1d0bbf0b5256e61;p=perl%2Fmodules%2FScope-Upper.git diff --git a/lib/Scope/Upper.pm b/lib/Scope/Upper.pm index 9202740..b5936db 100644 --- a/lib/Scope/Upper.pm +++ b/lib/Scope/Upper.pm @@ -9,13 +9,13 @@ Scope::Upper - Act on upper scopes. =head1 VERSION -Version 0.15 +Version 0.18 =cut our $VERSION; BEGIN { - $VERSION = '0.15'; + $VERSION = '0.18'; } =head1 SYNOPSIS @@ -24,7 +24,10 @@ L, L, L, L and L : package Scope; - use Scope::Upper qw; + use Scope::Upper qw< + reap localize localize_elem localize_delete + :words + >; sub new { my ($class, $name) = @_; @@ -66,22 +69,22 @@ 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 : @@ -109,6 +112,47 @@ L and L : 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 This module lets you defer actions I that will take place when the control flow returns into an upper scope. @@ -126,7 +170,15 @@ 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, and know which context was in use then with L ; + +=item * + +execute a subroutine in the setting of an upper subroutine stack frame with L ; + +=item * + +uniquely identify contextes with L and L. =back @@ -261,6 +313,142 @@ The previous example can then be "corrected" : will rightfully set C<$num> to C<26>. +=head2 C + +Executes the code reference C<$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. +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 + +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 => @_ => $cxt); + } + +Albeit the three exceptions listed above, it passes all the tests of L. + +=head2 C + +Returns an unique identifier (UID) for the context (or dynamic scope) pointed by C<$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} = $_; + } + + # %uids has 5 entries + +The UIDs are not guaranteed to be numbers, so you must use the C operator to compare them. + +To check whether a given UID is valid, you can use the L function. + +=head2 C + +Returns true if and only if C<$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 @@ -322,13 +510,13 @@ 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> : @@ -338,41 +526,44 @@ 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 and L point to depending on the C<$cxt>: sub { eval { sub { { - unwind @things => $cxt; + unwind @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 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'>. @@ -384,7 +575,13 @@ use base qw; our @EXPORT = (); our %EXPORT_TAGS = ( - funcs => [ qw ], + funcs => [ qw< + reap + localize localize_elem localize_delete + unwind want_at + uplevel + uid validate_uid + > ], words => [ qw ], consts => [ qw ], ); @@ -420,6 +617,29 @@ 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 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). @@ -430,6 +650,8 @@ 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.