match_param cannot be supplied with a dict in 1.2 and 1.3 branches as documented

[simonyarde]

Supplying a dict to the match_param of add_view results in the following error::

 File "/Users/simonyarde/development/pyramid/pyramid/pyramid/config/__init__.py", line 1093, in resolveConflicts
   L = unique.setdefault(discriminator, [])

TypeError: unhashable type: 'dict'

The discriminator tuple may not contain the match_param dict because dicts are mutable and therefore unhashable::

discriminator
('view', None, '', None, , None, None, None, 'test', None, False, None, None, None, {'test': '1'})

Pyramid passes it's own tests for match_param because resolveConflicts is not invoked:

test_match_param_from_dict (pyramid.tests.test_config.test_util.Test__make_predicates) ... ok
test_match_param_from_dict_fails (pyramid.tests.test_config.test_util.Test__make_predicates) ... ok
test_match_param_from_string (pyramid.tests.test_config.test_util.Test__make_predicates) ... ok
test_match_param_from_string_fails (pyramid.tests.test_config.test_util.Test__make_predicates) ... ok.

I quickly hacked mine by storing the string repr of match_param in the discriminator, which is ugly but works.

Perhaps it would be better to configure match_param with a tuple::

('foo=bar', 'b=2', 'c=3')

since python doesn't have an immutable dict object suitable for configuration purposes.

There would (probably) be no objection to changing configuration since this feature hasn't worked in 1.2 or 1.3 so there aren't any projects using it?

[mmerickel]

I think your proposal of using a tuple here is a good one. It'd be more consistent with the current behavior of request_method=('GET', 'POST').