X-Git-Url: http://git.vpit.fr/?a=blobdiff_plain;ds=inline;f=lib%2FScope%2FUpper.pm;h=3dad37b73a3255f9827bb09ab131e6c1c09a85b4;hb=refs%2Ftags%2Frt88174;hp=6128a8f10dd0fb906ca2663fa89215acffbd584b;hpb=ded0c62307dd417bbd7390457692310aca67ea93;p=perl%2Fmodules%2FScope-Upper.git
diff --git a/lib/Scope/Upper.pm b/lib/Scope/Upper.pm
index 6128a8f..3dad37b 100644
--- a/lib/Scope/Upper.pm
+++ b/lib/Scope/Upper.pm
@@ -9,58 +9,191 @@ Scope::Upper - Act on upper scopes.
=head1 VERSION
-Version 0.01
+Version 0.22
=cut
our $VERSION;
BEGIN {
- $VERSION = '0.01';
+ $VERSION = '0.22';
}
=head1 SYNOPSIS
- package X;
+L, L, L, L and L :
- use Scope::Upper qw/reap localize localize_elem/;
+ package Scope;
- sub desc { shift->{desc} }
+ use Scope::Upper qw<
+ reap localize localize_elem localize_delete
+ :words
+ >;
- sub set_tag {
- my ($desc) = @_;
+ sub new {
+ my ($class, $name) = @_;
- # First localize $x so that it gets destroyed last
- localize '$x' => bless({ desc => $desc }, __PACKAGE__) => 1;
+ localize '$tag' => bless({ name => $name }, $class) => 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";
- } => 1;
+ reap { print Scope->tag->name, ": end\n" } UP;
+ }
+
+ # 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('', @_));
- } => 1;
+ print Scope->tag->name, ': ', @_;
+ } => UP;
+ }
+
+ # 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 UserLand;
+
+ {
+ Scope->new("top"); # initializes $UserLand::tag
+
+ {
+ 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
+ }
+
+ } # prints "top: done"
+
+L and L :
+
+ package Try;
+
+ use Scope::Upper qw;
+
+ sub try (&) {
+ my @result = shift->();
+ my $cx = SUB UP; # Point to the sub above this one
+ unwind +(want_at($cx) ? @result : scalar @result) => $cx;
+ }
+
+ ...
+
+ sub zap {
+ try {
+ my @things = qw;
+ return @things; # returns to try() and then outside zap()
+ # not reached
+ };
+ # not reached
+ }
+
+ my @stuff = zap(); # @stuff contains qw
+ my $stuff = zap(); # $stuff contains 3
+
+L :
+
+ package Uplevel;
+
+ use Scope::Upper qw;
+
+ sub target {
+ faker(@_);
}
- package Y;
+ 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;
{
- X::set_tag('pie');
- # $x is now a X object
- warn 'what'; # warns "pie: what at ..."
+ $uid = uid();
+ {
+ if ($uid eq uid(UP)) { # yes
+ ...
+ }
+ if (validate_uid($uid)) { # yes
+ ...
+ }
+ }
+ }
+
+ if (validate_uid($uid)) { # no
...
- } # "pie: done" is printed
+ }
=head1 DESCRIPTION
-This module lets you defer actions that will take place when the control flow returns into an upper scope.
-Currently, you can hook an upper scope end, or localize variables and array/hash values in higher contexts.
+This module lets you defer actions I that will take place when the control flow returns into an upper scope.
+Currently, you can:
+
+=over 4
+
+=item *
+
+hook an upper scope end with L ;
+
+=item *
+
+localize variables, array/hash values or deletions of elements in higher contexts with respectively L, L and L ;
+
+=item *
+
+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
=head1 FUNCTIONS
+In all those functions, C<$context> refers to the target scope.
+
+You have to use one or a combination of L to build the C<$context> passed to these functions.
+This is needed in order to ensure that the module still works when your program is ran in the debugger.
+The only thing you can assume is that it is an I indicator of the frame, which means that you can safely store it at some point and use it when needed, and it will still denote the original scope.
+
=cut
BEGIN {
@@ -68,13 +201,20 @@ 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<$context> ends.
-Add a destructor that calls C<$callback> when the C<$level>-th upper scope ends, where C<0> corresponds to the current scope.
+=head2 C
-=head2 C
+ localize $what, $value;
+ localize $what, $value, $context;
-A C delayed to the time of first return into the C<$level>-th upper scope.
+Introduces a C delayed to the time of first return into the upper scope denoted by C<$context>.
C<$what> can be :
=over 4
@@ -91,53 +231,587 @@ A string beginning with a sigil, representing the symbol to localize and to assi
If the sigil is C<'$'>, L follows the same syntax as C, i.e. C<$value> isn't dereferenced.
For example,
- localize '$x', \'foo' => 0;
+ localize '$x', \'foo' => HERE;
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', $_[0] => UP }
+ }
+
+ {
+ package Tool;
+ {
+ Scope->new;
+ ...
+ }
+ }
- sub tag { localize '$x', $_[0] => 1; }
+will localize C<$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<$what> is a string denoting a variable that wasn't declared beforehand, the relevant slot will be vivified as needed and won't be deleted from the glob when the localization ends.
+This situation never arises with C because it only compiles when the localized variable is already declared.
+Although I believe it shouldn't be a problem as glob slots definedness is pretty much an implementation detail, this behaviour may change in the future if proved harmful.
=back
-=head2 C
+=head2 C
-Similar to L but for array and hash elements.
-If C<$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.
+ 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<$what> must be a string and the type of localization is inferred from its sigil.
+The two only valid types are array and hash ; for anything besides those, L will throw an exception.
C<$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.
+
+=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<$what> can be:
+
+=over 4
+
+=item *
+
+A glob, in which case C<$key> is ignored and the call is equivalent to C.
+
+=item *
+
+A string beginning with C<'@'> or C<'%'>, for which the call is equivalent to respectively C and C.
+
+=item *
+
+A string beginning with C<'&'>, which more or less does C in the upper scope.
+It's actually more powerful, as C<&func> won't even C anymore.
+C<$key> is ignored.
+
+=back
+
+=head2 C
+
+ 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
+
+ my $num = sub {
+ my @a = ('a' .. 'z');
+ unwind @a => HERE;
+ # not reached
+ }->();
+
+will set C<$num> to C<'z'>.
+You can use L to handle these cases.
+
+=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<$context> parameter is optional and defaults to the current context ; otherwise it is mandatory.
+
+L differs from L in that it can target I upper scope (besides a C substitution context) and not necessarily a sub, an eval or a format.
+Hence you can use it to return values from a C or a C fires depending on the C<$cxt> :
+
+ sub {
+ eval {
+ sub {
+ {
+ reap \&cleanup => $cxt;
+ ...
+ } # $cxt = SCOPE(0) = HERE
+ ...
+ }->(); # $cxt = SCOPE(1) = UP = SUB = CALLER(0)
+ ...
+ }; # $cxt = SCOPE(2) = UP UP = UP SUB = EVAL = CALLER(1)
+ ...
+ }->(); # $cxt = SCOPE(3) = SUB UP SUB = SUB EVAL = CALLER(2)
+ ...
+
+Where L, L and L act depending on the C<$cxt> :
+
+ sub {
+ eval {
+ sub {
+ {
+ localize '$x' => 1 => $cxt;
+ # $cxt = SCOPE(0) = HERE
+ ...
+ }
+ # $cxt = SCOPE(1) = UP = SUB = CALLER(0)
+ ...
+ }->();
+ # $cxt = SCOPE(2) = UP UP = UP SUB = EVAL = CALLER(1)
+ ...
+ };
+ # $cxt = SCOPE(3) = SUB UP SUB = SUB EVAL = CALLER(2)
+ ...
+ }->();
+ # $cxt = SCOPE(4), UP SUB UP SUB = UP SUB EVAL = UP CALLER(2) = TOP
+ ...
+
+Where L, L, L, L and L point to depending on the C<$cxt>:
+
+ sub {
+ eval {
+ sub {
+ {
+ unwind @things => $cxt; # or yield @things => $cxt
+ # or uplevel { ... } $cxt
+ ...
+ }
+ ...
+ }->(); # $cxt = SCOPE(0) = SCOPE(1) = HERE = UP = SUB = CALLER(0)
+ ...
+ }; # $cxt = SCOPE(2) = UP UP = UP SUB = EVAL = CALLER(1) (*)
+ ...
+ }->(); # $cxt = SCOPE(3) = SUB UP SUB = SUB EVAL = CALLER(2)
+ ...
+
+ # (*) Note that uplevel() will croak if you pass that scope frame,
+ # because it cannot target eval scopes.
=head1 EXPORT
-The functions L, L, L and L are only exported on request, either individually or by the tags C<':funcs'> and C<':all'>.
+The functions L, L, L, L, L, L, L, L, L and L are only exported on request, either individually or by the tags C<':funcs'> and C<':all'>.
+
+The constant L is also only exported on request, individually or by the tags C<':consts'> and C<':all'>.
+
+Same goes for the words L, L, L, L, L, L and L that are only exported on request, individually or by the tags C<':words'> and C<':all'>.
=cut
-use base qw/Exporter/;
+use base qw;
our @EXPORT = ();
our %EXPORT_TAGS = (
- funcs => [ qw/reap localize localize_elem TOPLEVEL/ ],
+ funcs => [ qw<
+ reap
+ localize localize_elem localize_delete
+ unwind yield leave
+ want_at context_info
+ uplevel
+ uid validate_uid
+ > ],
+ words => [ qw ],
+ consts => [ qw ],
);
our @EXPORT_OK = map { @$_ } values %EXPORT_TAGS;
$EXPORT_TAGS{'all'} = [ @EXPORT_OK ];
+=head1 CAVEATS
+
+Be careful that local variables are restored in the reverse order in which they were localized.
+Consider those examples:
+
+ local $x = 0;
+ {
+ reap sub { print $x } => HERE;
+ local $x = 1;
+ ...
+ }
+ # prints '0'
+ ...
+ {
+ local $x = 1;
+ reap sub { $x = 2 } => HERE;
+ ...
+ }
+ # $x is 0
+
+The first case is "solved" by moving the C before the C, and the second by using L instead of L.
+
+The effects of L, L and L can't cross C blocks, hence calling those functions in C is deemed to be useless.
+This is an hopeless case because C blocks are executed once while localizing constructs should do their job at each run.
+However, it's possible to hook the end of the current scope compilation with L.
+
+Some rare oddities may still happen when running inside the debugger.
+It may help to use a perl higher than 5.8.9 or 5.10.0, as they contain some context-related fixes.
+
+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 5.006).
=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.
@@ -146,7 +820,8 @@ 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
@@ -154,13 +829,17 @@ 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.
+Thanks to Shawn M. Moore for motivation.
+
=head1 COPYRIGHT & LICENSE
-Copyright 2008 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.