Add methods to read overloading

[schwern]

overload.pm has some functions which would be handy to have on any object.

• my $is_overloaded = $thing->is_overloaded()

Will return true if the object is overloaded, false otherwise. Just a thin wrapper around overloaded::Overloaded().

This should work on a class or object and go into lib/perl5i/2/Meta.pm.

• my $code = $thing->is_overloaded($op);

Returns the method which implements $op, if its overloaded. False otherwise. A thin wrapper around overload::Method()

Throw in some common terms for special operators.

string    => ""
numeric   => 0+

So $thing->is_overloaded("string") and $thing->is_overloaded(q[""]) are the same.

This should work on a class or object and go into lib/perl5i/2/Meta.pm.

• my $string = $object->something_something_something_str_val

Return the string value of the thing in the absence of overloading. A thin wrapper around overload::StrVal(). Don't know what the method should be called, it's kinda difficult to express. as_string_no_overload is descriptive but a bit awkward.

This should work on a object and go into lib/perl5i/2/Meta/Instance.pm.

• my $is_overloaded = $thing->is_string_overloaded

Returns the method $thing will respond with when used as a string. This has to check both string and numeric overloading, because the object will fall back to its numeric overloading if it's not string overloaded.

This should work on a class or object and go into lib/perl5i/2/Meta.pm.

You can take $has_string_overload from lib/perl5i/2/Meta.pm.

The name could use some work to differentiate it from $thing->is_overloaded("string"). Something which expresses it's true purpose, "will this return an overloaded value when used as a string" is subtly different from "does this have a string overload method".

[schwern]

Two I've found useful is is_string_overloaded() because both 0+ and "" have to be checked. Should that be its own method, or should is_overloaded() respond to things like "string" and "number"? I like the latter.

Also, it would be nice if there was a method to add an overload to a class, rather than go through the bletcherous "use overload" interface. It can also turn on fallback by default which 99% of them time is the right thing. Also it can respond to "string" and "numeric" in addition to the cryptic "" and 0+

[schwern]

Thinking about it, I'd rather "string" and "number" remain straight aliases for "" and 0+ to avoid it doing different things when getting or setting. So is_string_overloaded() special method it is.

[schwern]

I've updated the spec for this task and reduced its scope to just checking how an object is overloaded. Methods for adding overloading is more complicated and deserves its own issue.

[schwern]

A GCI student has claimed this, but I've not heard from them since. http://www.google-melange.com/gci/task/view/google/gci2011/7139304

[schwern]

@qrazhan is working on this as part of GCI