X-Git-Url: http://git.vpit.fr/?a=blobdiff_plain;f=lib%2FScope%2FUpper.pm;h=49d2aa4a5bef9c84ba51aeee9af046ab3dfa2bb3;hb=refs%2Fheads%2Fmaster;hp=eefe25362df85b9fdabf14a419e3351f9917434a;hpb=b2d82822b73f234e282b0e290b3cf0c783a65a99;p=perl%2Fmodules%2FScope-Upper.git
diff --git a/lib/Scope/Upper.pm b/lib/Scope/Upper.pm
index eefe253..49d2aa4 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 0.34
=cut
our $VERSION;
BEGIN {
- $VERSION = '0.16';
+ $VERSION = '0.34';
}
=head1 SYNOPSIS
@@ -24,7 +26,10 @@ L, L, L, L and L :
package Scope;
- use Scope::Upper qw;
+ use Scope::Upper qw<
+ reap localize localize_elem localize_delete
+ :words
+ >;
sub new {
my ($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 *
-execute a subroutine in the setting of an upper subroutine stack frame with L.
+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
@@ -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<$context> parameter is optional and defaults to the current context ; otherwise it is mandatory.
+
+L differs from L in that it can target I upper scope (besides a C substitution context) and not necessarily a sub, an eval or a format.
+Hence you can use it to return values from a C or a C, the upper context isn't coerced onto C<@values>.
+You can use the fifth value returned by L to handle context coercion.
+
+=head2 C
+
+ leave;
+ leave @values;
+
+Immediately returns C<@values> from the current block, whatever it may be (besides a C substitution context).
+C is actually a synonym for C, while C is a synonym for C.
+
+Like for L, you can use the fifth value returned by L to handle context coercion.
+
+=head2 C
-Like C, but for the subroutine/eval/format at or just above C<$context>.
+ my $want = want_at;
+ my $want = want_at $context;
-The previous example can then be "corrected" :
+Like L, but for the subroutine, eval or format context located at or just above C<$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<$context> is omitted, it defaults to the current context.
+
+The returned values are, in order :
+
+=over 4
+
+=item *
+
+I<(index 0)> : the namespace in use when the context was created ;
+
+=item *
+
+I<(index 1)> : the name of the file at the point where the context was created ;
+
+=item *
+
+I<(index 2)> : the line number at the point where the context was created ;
+
+=item *
+
+I<(index 3)> : the name of the subroutine called for this context, or C if this is not a subroutine context ;
+
+=item *
+
+I<(index 4)> : a boolean indicating whether a new instance of C<@_> was set up for this context, or C if this is not a subroutine context ;
+
+=item *
+
+I<(index 5)> : the context (in the sense of L) in which the context (in our sense) is executed ;
+
+=item *
+
+I<(index 6)> : the contents of the string being compiled for this context, or C if this is not an eval context ;
+
+=item *
+
+I<(index 7)> : a boolean indicating whether this eval context was created by C, or C if this is not an eval context ;
-Executes the code reference C<$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 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 {
@@ -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
@@ -365,44 +592,68 @@ 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>.
+If C<$from> points to the top-level scope in the current stack, then a warning is emitted and C<$from> is returned (see L for details).
+
+=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<$from> is returned if it is already a subroutine context ; hence C.
+If C<$from> already designates a subroutine context, then it is returned as-is ; hence C.
+If no subroutine context is present in the call stack, then a warning is emitted and the current context is returned (see L for details).
+
+=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<$from> is returned if it is already an eval context ; hence C.
+If C<$from> already designates an eval context, then it is returned as-is ; hence C.
+If no eval context is present in the call stack, then a warning is emitted and the current context is returned (see L for details).
=head2 Getting a context from a level
Here, C<$level> 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.
+If C<$level> points above the top-level scope in the current stack, then a warning is emitted and the top-level context is returned (see L for details).
+
+=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.
+If C<$level> points above the top-level scope in the current stack, then a warning is emitted and the top-level context is returned (see L for details).
=head2 Examples
@@ -414,13 +665,13 @@ Where L fires depending on the C<$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> :
@@ -430,44 +681,58 @@ 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,
# because it cannot target eval scopes.
+=head1 DIAGNOSTICS
+
+=head2 C
+
+This warning is emitted when L, L or L end up pointing to a context that is above the top-level context of the current stack.
+It indicates that you tried to go higher than the main scope, or to point across a C method, a signal handler, an overloaded or tied method call, a C statement or a C callback.
+In this case, the resulting context is the highest reachable one.
+
+=head2 C
+
+This warning is emitted when you ask for an L or L context and no such scope can be found in the call stack.
+The resulting context is the current one.
+
=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 +747,10 @@ 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 ],
@@ -493,6 +760,8 @@ $EXPORT_TAGS{'all'} = [ @EXPORT_OK ];
=head1 CAVEATS
+It is not possible to act upon a scope that belongs to another perl 'stack', i.e. to target a scope across a C method, a signal handler, an overloaded or tied method call, a C statement or a C callback.
+
Be careful that local variables are restored in the reverse order in which they were localized.
Consider those examples:
@@ -520,15 +789,40 @@ 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 when a custom runloop is used or when debugging flags are set with C.
-In those two cases, L will look for a C statement in its callback and, if there is one, throw an exception before executing the code.
+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 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.
+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.
+Starting from C 5.19.4, it is unfortunately no longer possible to reliably throw exceptions from L'd code while the debugger is in use.
+This may be solved in a future version depending on how the core evolves.
+
=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
@@ -545,7 +839,7 @@ L.
=head1 AUTHOR
-Vincent Pit, C<< >>, L.
+Vincent Pit C<< >>.
You can contact me by mail or on C (vincent).
@@ -560,17 +854,18 @@ You can find documentation for this module with the perldoc command.
perldoc Scope::Upper
-Tests code coverage report is available at L.
-
=head1 ACKNOWLEDGEMENTS
Inspired by Ricardo Signes.
+The reimplementation of a large part of this module for perl 5.24 was provided by David Mitchell.
+His work was sponsored by the Perl 5 Core Maintenance Grant from The Perl Foundation.
+
Thanks to Shawn M. Moore for motivation.
=head1 COPYRIGHT & LICENSE
-Copyright 2008,2009,2010,2011 Vincent Pit, all rights reserved.
+Copyright 2008,2009,2010,2011,2012,2013,2014,2015,2016,2017,2018,2019,2021,2023 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.