for (1 .. 5) {
sub {
eval {
- # create Scope::Context objects
+ # Create Scope::Context objects for different upper frames.
my ($block, $sub, $eval, $loop);
{
$block = Scope::Context->new;
# This prints "hello" when the eval block above ends.
$eval->reap(sub { print "hello\n" });
- # Ignore $SIG{__DIE__} just for the loop.
+ # Ignore $SIG{__DIE__} just for the loop body.
$loop->localize_delete('%SIG', '__DIE__');
# Execute the callback as if it ran in place of the sub.
# Immediately return (1, 2, 3) from the sub, bypassing the eval.
$sub->unwind(@values, 3);
+
+ # Not reached.
}
+
+ # Not reached.
}->();
+
+ # unwind() returns here. "hello\n" was printed, and now
+ # $SIG{__DIE__} is undefined.
}
=head1 DESCRIPTION
The L<Scope::Context> methods actually do more than their subroutine counterparts from L<Scope::Upper> : before each call, the target context will be checked to ensure it is still active (which means that it is still present in the current call stack), and an exception will be thrown if you attempt to act on a context that has already expired.
This means that :
- my $sc;
+ my $cxt;
{
- $sc = Scope::Context->new;
+ $cxt = Scope::Context->new;
}
- $sc->reap(sub { print "hello\n });
+ $cxt->reap(sub { print "hello\n });
will croak when L</reap> is called.
=head1 METHODS
-=head2 C<new [ $context ]>
+=head2 C<new>
+
+ my $cxt = Scope::Context->new;
+ my $cxt = Scope::Context->new($scope_upper_cxt);
Creates a new immutable L<Scope::Context> object from the L<Scope::Upper>-comptabile context C<$context>.
If omitted, C<$context> defaults to the current context.
=head2 C<cxt>
+ my $scope_upper_cxt = $cxt->cxt;
+
Read-only accessor to the L<Scope::Upper> context corresponding to the topic L<Scope::Context> object.
=head2 C<uid>
+ my $uid = $cxt->uid;
+
Read-only accessor to the L<Scope::Upper> UID of the topic L<Scope::Context> object.
=cut
=head2 C<is_valid>
+ my $is_valid = $cxt->is_valid;
+
Returns true if and only if the topic context is still valid (that is, it designates a scope that is higher than the topic context in the call stack).
=cut
=head2 C<assert_valid>
+ $cxt->assert_valid;
+
Throws an exception if the topic context has expired and is no longer valid.
Returns true otherwise.
=head2 C<want>
+ my $want = $cxt->want;
+
Returns the Perl context (in the sense of C<wantarray> : C<undef> for void context, C<''> for scalar context, and true for list context) in which is executed the scope corresponding to the topic L<Scope::Context> object.
=cut
Scope::Upper::want_at($self->cxt);
}
-=head2 C<up [ $frames ]>
+=head2 C<up>
+
+ my $up_cxt = $cxt->up;
+ my $up_cxt = $cxt->up($frames);
+ my $up_cxt = Scope::Context->up;
Returns a new L<Scope::Context> object pointing to the C<$frames>-th upper scope above the topic context.
sub up {
my ($self, $frames) = @_;
+ my $cxt;
if (Scalar::Util::blessed($self)) {
$self->assert_valid;
+ $cxt = $self->cxt;
} else {
- $self = $self->new(Scope::Upper::UP(Scope::Upper::SUB()));
+ $cxt = Scope::Upper::UP(Scope::Upper::SUB());
}
$frames = 1 unless defined $frames;
- my $cxt = $self->cxt;
$cxt = Scope::Upper::UP($cxt) for 1 .. $frames;
$self->new($cxt);
}
-=head2 C<sub [ $frames ]>
+=head2 C<sub>
+
+ my $sub_cxt = $cxt->sub;
+ my $sub_cxt = $cxt->sub($frames);
+ my $sub_cxt = Scope::Context->sub;
Returns a new L<Scope::Context> object pointing to the C<$frames>-th subroutine scope above the topic context.
}
sub inner {
- my $sub = Scope::Context->new->sub(1); # = Scope::Context->sub
+ my $sub = Scope::Context->new->sub(1); # = Scope::Context->sub(1)
# $sub points to the context for the outer() sub.
}
sub sub {
my ($self, $frames) = @_;
+ my $cxt;
if (Scalar::Util::blessed($self)) {
$self->assert_valid;
+ $cxt = $self->cxt;
} else {
- $self = $self->new(Scope::Upper::UP(Scope::Upper::SUB()));
+ $cxt = Scope::Upper::UP(Scope::Upper::SUB());
}
$frames = 0 unless defined $frames;
- my $cxt = Scope::Upper::SUB($self->cxt);
+ $cxt = Scope::Upper::SUB($cxt);
$cxt = Scope::Upper::SUB(Scope::Upper::UP($cxt)) for 1 .. $frames;
$self->new($cxt);
}
-=head2 C<eval [ $frames ]>
+=head2 C<eval>
+
+ my $eval_cxt = $cxt->eval;
+ my $eval_cxt = $cxt->eval($frames);
+ my $eval_cxt = Scope::Context->eval;
Returns a new L<Scope::Context> object pointing to the C<$frames>-th C<eval> scope above the topic context.
sub eval {
my ($self, $frames) = @_;
+ my $cxt;
if (Scalar::Util::blessed($self)) {
$self->assert_valid;
+ $cxt = $self->cxt;
} else {
- $self = $self->new(Scope::Upper::UP(Scope::Upper::SUB()));
+ $cxt = Scope::Upper::UP(Scope::Upper::SUB());
}
$frames = 0 unless defined $frames;
- my $cxt = Scope::Upper::EVAL($self->cxt);
+ $cxt = Scope::Upper::EVAL($cxt);
$cxt = Scope::Upper::EVAL(Scope::Upper::UP($cxt)) for 1 .. $frames;
$self->new($cxt);
}
-=head2 C<reap $code>
+=head2 C<reap>
+
+ $cxt->reap($code);
Execute C<$code> when the topic context ends.
&Scope::Upper::reap($code, $self->cxt);
}
-=head2 C<localize $what, $value>
+=head2 C<localize>
+
+ $cxt->localize($what, $value);
Localize the variable described by C<$what> to the value C<$value> when the control flow returns to the scope pointed by the topic context.
Scope::Upper::localize($what, $value, $self->cxt);
}
-=head2 C<localize_elem $what, $key, $value>
+=head2 C<localize_elem>
+
+ $cxt->localize_elem($what, $key, $value);
Localize the element C<$key> of the variable C<$what> to the value C<$value> when the control flow returns to the scope pointed by the topic context.
Scope::Upper::localize_elem($what, $key, $value, $self->cxt);
}
-=head2 C<localize_delete $what, $key>
+=head2 C<localize_delete>
+
+ $cxt->localize_delete($what, $key);
Delete the element C<$key> from the variable C<$what> when the control flow returns to the scope pointed by the topic context.
Scope::Upper::localize_delete($what, $key, $self->cxt);
}
-=head2 C<unwind @values>
+=head2 C<unwind>
+
+ $cxt->unwind(@values);
Immediately returns the scalars listed in C<@values> from the closest subroutine enclosing the topic context.
Scope::Upper::unwind(@_ => $self->cxt);
}
-=head2 C<uplevel $code, @args>
+=head2 C<uplevel>
+
+ my @ret = $cxt->uplevel($code, @args);
Executes the code reference C<$code> with arguments C<@args> in the same setting as the closest subroutine enclosing the topic context, then returns to the current scope the values returned by C<$code>.
=head1 COPYRIGHT & LICENSE
-Copyright 2011 Vincent Pit, all rights reserved.
+Copyright 2011,2012 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.
projects / perl / modules / Scope-Context.git / blobdiff