package Sub::Nary;
-use 5.008001;
+use 5.008_001;
use strict;
use warnings;
use Sub::Nary;
- my $sn = Sub::Nary->new();
+ my $sn = Sub::Nary->new;
my $r = $sn->nary(\&hlagh);
=head1 DESCRIPTION
-This module uses the L<B> framework to walk into subroutines and try to guess how many scalars are likely to be returned in list context. It's not always possible to give a definitive answer to this question at compile time, so the results are given in terms of "probability of return" (to be understood in a sense described below).
+This module uses the L<B> framework to walk into subroutines and try to guess how many scalars are likely to be returned in list context.
+It's not always possible to give a definitive answer to this question at compile time, so the results are given in terms of "probability of return" (to be understood in a sense described below).
=head1 METHODS
=head2 C<new>
-The usual constructor. Currently takes no argument.
+ my $sn = Sub::Nary->new;
-=head2 C<nary $coderef>
+The usual constructor.
+Currently takes no argument.
-Takes a code reference to a named or anonymous subroutine, and returns a hash reference whose keys are the possible numbers of returning scalars, and the corresponding values the "probability" to get them. The special key C<'list'> is used to denote a possibly infinite number of returned arguments. The return value hence would look at
+=head2 C<nary>
+
+ my $res = $sn->nary($coderef);
+
+Takes a reference to a named or anonymous subroutine, and returns a hash reference whose keys are the possible numbers of returning scalars, and the corresponding values the "probability" to get them.
+The special key C<'list'> is used to denote a possibly infinite number of returned arguments.
+The return value hence would look at
{ 1 => 0.2, 2 => 0.4, 4 => 0.3, list => 0.1 }
-that is, we should get C<1> scalar C<1> time over C<5> and so on. The sum of all values is C<1>. The returned result, and all the results obtained from intermediate subs, are cached into the object.
+that is, we should get C<1> scalar C<1> time over C<5> and so on.
+The sum of all values is C<1>.
+The returned result, and all the results obtained from intermediate subs, are cached into the object.
=head2 C<flush>
-Flushes the L<Sub::Nary> object cache. Returns the object itself.
+Flushes the L<Sub::Nary> object cache.
+Returns the object itself.
=head1 PROBABILITY OF RETURN
=over 4
-=item * When branching, each branch is considered equally possible.
+=item *
+
+When branching, each branch is considered equally possible.
For example, the subroutine
it is considered to return C<3> scalars with probability C<1/2>, C<2> with probability C<1/2 * 1/2 = 1/4> and C<1> (when the two tests fail, the last computed value is returned, which here is C<< $x > 0.9 >> evaluated in the scalar context of the test) with remaining probability C<1/4>.
-=item * The total probability law for a given returning point is the convolution product of the probabilities of its list elements.
+=item *
-As such,
+The total probability law for a given returning point is the convolution product of the probabilities of its list elements.
+
+As such,
sub notsosimple {
return 1, simple(), 2
never returns C<1> argument but returns C<2> with probability C<1/2 * 1/2 = 1/4>, C<3> with probability C<1/2 * 1/2 + 1/2 * 1/2 = 1/2> and C<4> with probability C<1/4> too.
-=item * If a core function may return different numbers of scalars, each kind is considered equally possible.
+=item *
+
+If a core function may return different numbers of scalars, each kind is considered equally possible.
+
+For example, C<stat> returns C<13> elements on success and C<0> on error.
+The according probability will then be C<< { 0 => 0.5, 13 => 0.5 } >>.
-For example, C<stat> returns C<13> elements on success and C<0> on error. The according probability will then be C<< { 0 => 0.5, 13 => 0.5 } >>.
+=item *
-=item * The C<list> state is absorbing in regard of all the other ones.
+The C<list> state is absorbing in regard of all the other ones.
This is just a pedantic way to say that "list + fixed length = list".
That's why
my $r = add $self->inspect($op->first);
shift @{$self->{cv}};
- $r = { $r => 1 } unless ref $r;
$self->{cache}->{$tag} = { %$r };
return undef, $r;
}
my ($self, $op) = @_;
$op = $op->first while $op->flags & OPf_KIDS;
- return undef, 0 if null $op;
- if (name($op) eq 'pushmark') {
- $op = $op->sibling;
- return undef, 0 if null $op;
- }
+ # First must be a pushmark
+ $op = $op->sibling;
+ # Next must be non null - at worse it's the rv2cv
my $r;
my $c = 1;
L<perl> 5.8.1.
-L<Carp> (standard since perl 5), L<B> (since perl 5.005) and L<XSLoader> (since perl 5.006).
+L<Carp> (standard since perl 5), L<B> (since perl 5.005) and L<XSLoader> (since perl 5.6.0).
=head1 AUTHOR
Vincent Pit, C<< <perl at profvince.com> >>, L<http://www.profvince.com>.
-You can contact me by mail or on #perl @ FreeNode (vincent or Prof_Vince).
+You can contact me by mail or on C<irc.perl.org> (vincent).
=head1 BUGS
-Please report any bugs or feature requests to C<bug-sub-nary at rt.cpan.org>, or through the web interface at L<http://rt.cpan.org/NoAuth/ReportBug.html?Queue=Sub-Nary>. 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<bug-sub-nary at rt.cpan.org>, or through the web interface at L<http://rt.cpan.org/NoAuth/ReportBug.html?Queue=Sub-Nary>.
+I will be notified, and then you'll automatically be notified of progress on your bug as I make changes.
=head1 SUPPORT
projects / perl / modules / Sub-Nary.git / blobdiff