X-Git-Url: http://git.vpit.fr/?a=blobdiff_plain;ds=inline;f=lib%2FScope%2FUpper.pm;h=04f26fdd395262f4d2fe5d97bed5abe66fa4d6cb;hb=97dc8ef80311dba0ff5058c2ee54caa8193b5c51;hp=63ca3bf77245e994384b12bec989e4d2a497eda0;hpb=daa5478303f254eff6015045396920baafee0688;p=perl%2Fmodules%2FScope-Upper.git
diff --git a/lib/Scope/Upper.pm b/lib/Scope/Upper.pm
index 63ca3bf..04f26fd 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 0.14
+Version 0.26
=cut
our $VERSION;
BEGIN {
- $VERSION = '0.14';
+ $VERSION = '0.26';
}
=head1 SYNOPSIS
@@ -24,7 +26,10 @@ L, L, L, L and L :
package Scope;
- use Scope::Upper qw;
+ use Scope::Upper qw<
+ reap localize localize_elem localize_delete
+ :words
+ >;
sub new {
my ($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 :
@@ -109,6 +114,47 @@ 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 +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
@@ -145,11 +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 :
@@ -199,7 +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<$what> must be a string and the type of localization is inferred from its sigil.
@@ -208,7 +276,10 @@ C<$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<$what> can be:
@@ -221,7 +292,7 @@ A glob, in which case C<$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 *
@@ -231,9 +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<$context> parameter is optional and defaults to the current context (making the call equivalent to a bare C) ; otherwise it is mandatory.
The upper context isn't coerced onto C<@values>, which is hence always evaluated in list context.
This means that
@@ -247,11 +322,49 @@ This means that
will set C<$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<$context> parameter is optional and defaults to the current context ; otherwise it is mandatory.
+
+L differs from L in that it can target I upper scope (besides a C substitution context) and not necessarily a sub, an eval or a format.
+Hence you can use it to return values from a C or a C, the upper context isn't coerced onto C<@values>.
+You can use the fifth value returned by L to handle context coercion.
+
+=head2 C
+
+ leave;
+ leave @values;
-Like C, but for the subroutine/eval/format at or just above C<$context>.
+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.
-The previous example can then be "corrected" :
+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 $num = sub {
my @a = ('a' .. 'z');
@@ -261,6 +374,212 @@ The previous example can then be "corrected" :
will rightfully set C<$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
=head2 C
@@ -273,27 +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<$from> is returned if it is already an eval context ; hence C.
@@ -303,11 +635,17 @@ Note that C<$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.
@@ -322,13 +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> :
@@ -338,41 +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'>.
@@ -384,7 +726,14 @@ use base qw;
our @EXPORT = ();
our %EXPORT_TAGS = (
- funcs => [ qw ],
+ funcs => [ qw<
+ reap
+ localize localize_elem localize_delete
+ unwind yield leave
+ want_at context_info
+ uplevel
+ uid validate_uid
+ > ],
words => [ qw ],
consts => [ qw ],
);
@@ -420,9 +769,37 @@ 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
@@ -430,6 +807,8 @@ 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.
@@ -462,7 +841,7 @@ Thanks to Shawn M. Moore for motivation.
=head1 COPYRIGHT & LICENSE
-Copyright 2008,2009,2010,2011 Vincent Pit, all rights reserved.
+Copyright 2008,2009,2010,2011,2012,2013,2014,2015 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.