X-Git-Url: http://git.vpit.fr/?a=blobdiff_plain;f=lib%2FScope%2FUpper.pm;h=acd566b0f7588a166d2cf460f3e7f1f76f33492b;hb=d965a45a64e2aab24e3adbda18543e80a0b81e57;hp=e5f22c97671028619a9e51d619476a295f77e88d;hpb=e5ece1843f061be7de19ba4bacdd247e0d05c2b9;p=perl%2Fmodules%2FScope-Upper.git diff --git a/lib/Scope/Upper.pm b/lib/Scope/Upper.pm index e5f22c9..acd566b 100644 --- a/lib/Scope/Upper.pm +++ b/lib/Scope/Upper.pm @@ -9,60 +9,135 @@ Scope::Upper - Act on upper scopes. =head1 VERSION -Version 0.02 +Version 0.13 =cut our $VERSION; BEGIN { - $VERSION = '0.02'; + $VERSION = '0.13'; } =head1 SYNOPSIS - package X; +L, L, L, L and L : - use Scope::Upper qw/reap localize localize_elem localize_delete/; + package Scope; - sub desc { shift->{desc} } + use Scope::Upper qw/reap localize localize_elem localize_delete :words/; - sub set_tag { - my ($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; + } - localize_delete '@ARGV', $#ARGV => 1; # delete last @ARGV element + # 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 Y; + ... + + package UserLand; { - X::set_tag('pie'); - # $x is now a X object, and @ARGV has one element less - warn 'what'; # warns "pie: what at ..." - ... - } # "pie: done" is printed + 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/unwind want_at :words/; + + 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/a b c/; + return @things; # returns to try() and then outside zap() + # not reached + }; + # not reached + } + + my @stuff = zap(); # @stuff contains qw/a b c/ + my $stuff = zap(); # $stuff contains 3 =head1 DESCRIPTION -This module lets you defer actions that will take place when the control flow returns into an upper scope. -Currently, you can hook an upper scope end, or localize variables, array/hash values or deletions of elements in higher contexts. +This module lets you defer actions I that will take place when the control flow returns into an upper scope. +Currently, you can: + +=over 4 + +=item * + +hook an upper scope end with L ; + +=item * + +localize variables, array/hash values or deletions of elements in higher contexts with respectively L, L and L ; + +=item * + +return values immediately to an upper level with L, and know which context was in use then with L. + +=back =head1 FUNCTIONS +In all those functions, C<$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 { @@ -70,13 +145,13 @@ BEGIN { XSLoader::load(__PACKAGE__, $VERSION); } -=head2 C +=head2 C -Add a destructor that calls C<$callback> when the C<$level>-th upper scope ends, where C<0> corresponds to the current scope. +Adds a destructor that calls C<$callback> (in void context) when the upper scope represented by C<$context> ends. -=head2 C +=head2 C -A C delayed to the time of first return into the C<$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 @@ -93,29 +168,49 @@ 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', $_[0] => UP } + } - sub tag { localize '$x', $_[0] => 1; } + { + package Tool; + { + Scope->new; + ... + } + } + +will localize C<$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<$value> is ; otherwise it's inferred from the sigil. +Introduces a C or C delayed to the time of first return into the upper scope denoted by C<$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<$what> is a string pointing to an undeclared variable, the variable will be vivified as soon as the localization occurs and emptied when it ends, although it will still exist in its glob. -Similiar to L, but for deleting variables or array/hash elements. +=head2 C + +Introduces the deletion of a variable or an array/hash element delayed to the time of first return into the upper scope denoted by C<$context>. C<$what> can be: =over 4 @@ -136,13 +231,152 @@ C<$key> is ignored. =back -=head2 C +=head2 C + +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 the level that currently represents the highest scope. +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 + +Like C, but for the subroutine/eval/format at or just above C<$context>. + +The previous example can then be "corrected" : + + my $num = sub { + my @a = ('a' .. 'z'); + unwind +(want_at(HERE) ? @a : scalar @a) => HERE; + # not reached + }->(); + +will rightfully set C<$num> to C<26>. + +=head1 CONSTANTS + +=head2 C + +True iff the module could have been built when thread-safety features. + +=head1 WORDS + +=head2 Constants + +=head3 C + +Returns the context that currently represents the highest scope. + +=head3 C + +The context of the current scope. + +=head2 Getting a context from a context + +For any of those functions, C<$from> is expected to be a context. +When omitted, it defaults to the the current context. + +=head3 C + +The context of the scope just above C<$from>. + +=head3 C + +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 + +The context of the closest eval above C<$from>. +Note that C<$from> is returned if it is already an eval context ; hence C. + +=head2 Getting a context from a level + +Here, C<$level> should denote a number of scopes above the current one. +When omitted, it defaults to C<0> and those functions return the same context as L. + +=head3 C + +The C<$level>-th upper context, regardless of its type. + +=head3 C + +The context of the C<$level>-th upper subroutine/eval/format. +It kind of corresponds to the context represented by C, but while e.g. C refers to the caller context, C will refer to the top scope in the current context. + +=head2 Examples + +Where L fires depending on the C<$cxt> : + + sub { + eval { + sub { + { + reap \&cleanup => $cxt; + ... + } # $cxt = SCOPE(0), or HERE + ... + }->(); # $cxt = SCOPE(1), or UP, or SUB, or CALLER, or CALLER(0) + ... + }; # $cxt = SCOPE(2), or UP UP, or UP SUB, or EVAL, or CALLER(1) + ... + }->(); # $cxt = SCOPE(3), or SUB UP SUB, or SUB EVAL, or CALLER(2) + ... + +Where L, L and L act depending on the C<$cxt> : + + sub { + eval { + sub { + { + localize '$x' => 1 => $cxt; + # $cxt = SCOPE(0), or HERE + ... + } + # $cxt = SCOPE(1), or UP, or SUB, or CALLER, or CALLER(0) + ... + }->(); + # $cxt = SCOPE(2), or UP UP, or UP SUB, or EVAL, or CALLER(1) + ... + }; + # $cxt = SCOPE(3), or SUB UP SUB, or SUB EVAL, or CALLER(2) + ... + }->(); + # $cxt = SCOPE(4), UP SUB UP SUB, or UP SUB EVAL, or UP CALLER(2), or TOP + ... + +Where L and L point to depending on the C<$cxt>: + + sub { + eval { + sub { + { + unwind @things => $cxt; + ... + } + ... + }->(); # $cxt = SCOPE(0 .. 1), or HERE, or UP, or SUB, or CALLER(0) + ... + }; # $cxt = SCOPE(2), or UP UP, or UP SUB, or EVAL, or CALLER(1) + ... + }->(); # $cxt = SCOPE(3), or SUB UP SUB, or SUB EVAL, or CALLER(2) + ... =head1 EXPORT -The functions L, L, L, L and L are only exported on request, either individually or by the tags C<':funcs'> and C<':all'>. +The functions L, L, L, L, L and L are only exported on request, either individually or by the tags C<':funcs'> and C<':all'>. + +The constant L is also only exported on request, individually or by the tags C<':consts'> and C<':all'>. + +Same goes for the words L, L, L, L, L, L and L that are only exported on request, individually or by the tags C<':words'> and C<':all'>. =cut @@ -150,7 +384,9 @@ use base qw/Exporter/; our @EXPORT = (); our %EXPORT_TAGS = ( - funcs => [ qw/reap localize localize_elem localize_delete TOPLEVEL/ ], + funcs => [ qw/reap localize localize_elem localize_delete unwind want_at/ ], + words => [ qw/TOP HERE UP SUB EVAL SCOPE CALLER/ ], + consts => [ qw/SU_THREADSAFE/ ], ); our @EXPORT_OK = map { @$_ } values %EXPORT_TAGS; $EXPORT_TAGS{'all'} = [ @EXPORT_OK ]; @@ -162,7 +398,7 @@ Consider those examples: local $x = 0; { - reap sub { print $x } => 0; + reap sub { print $x } => HERE; local $x = 1; ... } @@ -170,15 +406,19 @@ Consider those examples: ... { local $x = 1; - reap sub { $x = 2 } => 0; + 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. -L, L and L effects can't cross C blocks, hence calling those functions in C is deemed to be useless. +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. =head1 DEPENDENCIES @@ -186,8 +426,15 @@ L (standard since perl 5.006). =head1 SEE ALSO +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. @@ -196,7 +443,8 @@ 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 @@ -210,9 +458,11 @@ Tests code coverage report is available at L