Revision history for Safe-Isa
+ - added new interface: $obj->$_call_if_can
+
1.000006 - 2016-10-31
- now falling back to $obj->isa if DOES/does is not implemented on the
object, to avoid fatal errors on perls too old to have their own DOES
our $VERSION = '1.000006';
-our @EXPORT = qw($_call_if_object $_isa $_can $_does $_DOES);
+our @EXPORT = qw($_call_if_object $_isa $_can $_does $_DOES $_call_if_can);
our $_call_if_object = sub {
my ($obj, $method) = (shift, shift);
sub { my $obj = shift; $obj->$_call_if_object($method => @_) }
} qw(isa can does DOES);
+our $_call_if_can = sub {
+ my ($obj, $method) = (shift, shift);
+ $obj->$_call_if_object(can => $method) && $obj->$_call_if_object($method => @_);
+};
+
1;
__END__
$maybe_an_object->$_does('RoleName'); # true or false, no boom today
$maybe_an_object->$_DOES('RoleName'); # true or false, no boom today
-And just in case we missed a method:
+And just in case we missed a method or two:
$maybe_an_object->$_call_if_object(name => @args);
+ $maybe_an_object->$_call_if_can(name => @args);
Or to re-use a previous example for purposes of explication:
If called on an object, calls C<method_name> on it and returns the result,
otherwise returns nothing.
+=head2 $_call_if_can
+
+ $maybe_an_object->$_call_if_can(name => @args);
+
+If called on an object, calls C<can> on it; if that returns true, then
+calls C<method_name> on it and returns the result; if any condition is false
+returns nothing.
+
=head1 SEE ALSO
I gave a lightning talk on this module (and L<curry> and L<Import::Into>) at
use strict;
use warnings;
-use Test::More tests => 28;
+use Test::More tests => 38;
{ package Foo; sub new { bless({}, $_[0]) } }
{ package Bar; our @ISA = qw(Foo); sub bar { $_[1] } }
is($bar->$_call_if_object(bar => 2), 2, 'bar $_call_if_object(bar => 2)');
ok(eval { is($blam->$_call_if_object(isa => 'Foo'), undef, 'blam can\'t call anything'); 1 }, 'no boom today');
ok(eval { is($undef->$_call_if_object(isa => 'Foo'), undef, 'undef can\'t call anything'); 1 }, 'and no boom tomorrow either');
+
+ok($foo->$_call_if_can(isa => 'Foo'), 'foo $_call_if_can(isa => Foo)');
+ok($bar->$_call_if_can(isa => 'Foo'), 'bar $_call_if_can(isa => Foo)');
+ok(eval { is($foo->$_call_if_can(bar => ), undef, 'foo can\'t call bar'); 1 }, 'no boom today');
+is($bar->$_call_if_can(bar => ), undef, 'bar $_call_if_can(bar => ');
+is($bar->$_call_if_can(bar => 2), 2, 'bar $_call_if_can(bar => 2');
+ok(eval { is($blam->$_call_if_can(isa => 'Foo'), undef, 'blam can\'t call anything'); 1 }, 'no boom today');
+ok(eval { is($undef->$_call_if_can(isa => 'Foo'), undef, 'undef can\'t call anything'); 1 }, 'and no boom tomorrow either');