I am duplicating my use.perl comment (http://use.perl.org/~Ovid/journal/38885
) here since I think this is a better forum (and use.perl is such a
massive pile of crap and incredibly annoying to comment on).
--
Actually, I said no to the idea of:
with 'Role::Serializable' => { includes => [] };
meaning "don't compose any methods, but i still want to do this role",
because I think that it is not very clear and could very easily be
confusing to people. After all you would never say:
with 'Role::Serializable' => { excludes => [] };
it just wouldn't make sense. I just really never liked APIs where the
lack of something was significantly meaningful.
Now, all that said, I actually really kind of like:
with 'Role::Serializable' => { includes => [ 'to_xml' ] };
because it is clear and obvious and pretty useful. In fact, if you had
proposed this originally, and not tied it to the includes => [] being
a shortcut to a "interface" type role, I would probably have said "go
for it".
In fact, I would be happy to accept a fork (no more patches now that
we are on git) which implemented includes => [ 'to_xml' ] (along with
tests and docs of course) as long as it didn't do the "interface" role
shortcut thing.
- Stevan
On Apr 28, 2009, at 8:59 AM, Ovid wrote:
----- Original Message ----
From: Stevan Little <stevan.lit...@iinteractive.com>
I am also very much not a fan of adding features to solve problems
that are
easily solved in other ways. Moose already has a fairly large
feature set and I
am pretty adverse to adding more unless they are first vetted
through a MooseX::
module (see the section on NEW FEATURES in
Moose::Manual::Contributing).
I don't particularly care for the idea of creating an interface role
for every role which might also serve as an interface because that
violates chromatic's insistence that things be easy lest we
discourage people from using roles to their full power.
That being said, I'll look at the MooseX route. Thanks.
By the way, was this really a bug?
#!/usr/bin/env perl
package My::Role;
use Moose::Role;
sub foo { __PACKAGE__ }
package Bar;
use Moose;
with 'My::Role' => { excludes => 'foo' };
print Bar->foo;
# Can't locate object method "foo" via package "Bar" at role.pl
line 13.
That shouldn't be a runtime issue, but a composition time failure.
Should I file a bug report?
Cheers,
Ovid
--
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- Stevan
On Apr 28, 2009, at 3:53 AM, Ovid wrote:
There are times that you want to use a role, but only as an
interface.
If 9 out of 10 classes use the implementation, it's annoying to have
that 10th class have to do this:
with 'My::Role' => { excludes => \...@a_long_list_of_methods };
What about something like this?
with 'My::Role' => { includes => [] };
That
would be the mutually exclusive opposite of 'excludes'. No methods
would be composed into your class, but they would all be added to
the
'requires' list. This (I think) would largely overcome chromatic's
objection (http://use.perl.org/comments.pl?sid=42835&cid=68295)
that if someone wants to use a role as an interface, being forced to
manually exclude every method is annoying and would discourage role
use. So a role could be trivially used as an interface, if desired,
even if implementation is provided.
Plus, if you still needed two of the 8 methods a role provided:
with 'My::Role' => { includes => [qw{ foo bar }] };
Seems to me that this is the best of both worlds. This would also
make it
trivial to add the "warn on conflict" back in because the entire
objection
seemed to be that the warning coupled with it being annoying to
exclude all
methods would discourage role use (an argument which penalizes the
programmer
who values safety and correctness, but then, Dominus doesn't like
how we
constantly encourage "use strict", either). While I do realize
I've lost this
argument, at least adding "includes" would make roles a tad more
flexible and
make some of my work easier if I get around to writing
"MooseX::Role::Strict".
This
also shows what I *think* is a limitation in 'excludes'. All
methods
listed in a role should be explicitly added to the 'requires' list.
The following is a runtime failure:
#!/usr/bin/env perl
package My::Role;
use Moose::Role;
sub foo { __PACKAGE__ }
package Bar;
use Moose;
with 'My::Role' => { excludes => 'foo' };
print Bar->foo;
# Can't locate object method "foo" via package "Bar" at role.pl
line 13.
Thoughts?
Cheers,
Ovid
--
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