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Re: [perl #114460] RFE: class as conditional self-defining keywordfor package

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David Golden
August 12, 2012 13:29
Re: [perl #114460] RFE: class as conditional self-defining keywordfor package
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On Sun, Aug 12, 2012 at 1:08 PM, Linda Walsh <> wrote:
> [snip]
> border between classes and packages, and the fear of 'use <pkgname>'
> trying to use 'auto-semantics' to determine if it should look for
> pkgname in the LIB list.

My view is that there is *no* border between classes and packages,
because the former has no (current) meaning in Perl 5.  A "class" is
just a namespace, i.e. a package, that happens to have a reference
blessed to it.

There is an often blurry border between "package" (namespace) and
"module" (a .pm file).  E.g. both "use" and "require" can load a
module, which may or may not contain a package of the corresponding

I.e. a module contains zero or more package declarations; these may or
may not correspond to the bareword "name" of the module before it is
translated into a path to search @INC.

So, with that in mind, I could see benefit in trying to clarify what
people intend, and to allow people to "use" a bareword without needing
to worry whether it's in a module or already loaded as part of another
module.  However, I don't think "class" is an appropriate keyword for
it, as that already has lots of overloaded meanings (and desired
meanings) and I don't see this specific feature consistent with or
clarifying any of those.

I do think it would be appropriate to prototype such a capability on
CPAN and see if there is widespread adoption.

For example, this would be trivially easy and less verbose than direct
%INC hacking:

    package Foo::Bar;
    use Inc::Loaded;  # import sets caller as loaded in %INC

A more sophisticated approach could use the hoookable parser to do this:

    use Devel::InnerClass;

    innerclass Foo::Bar {

(The phrase "innerclass" seems less likely to conflict with what
people expect of a "class" keyword.)

I tend to think either of those would be better places to start than
by adding a new keyword to the core.

-- David

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