Loader dumper objects api

[ingydotnet]

Depends on #561

[perlpunk]

I would write a wrapper for this. Not sure about a good name.

[perlpunk]

Do you plan to add the resolvers and representers in this PR, too?

[perlpunk]

Could be easier to delete the constructor when doing add_constructor(tag, None)? Then this check wouldn't be necessary

[perlpunk]

The None part of the multi_constructors below is not yet supported

[perlpunk]

Maybe it would be clearer to do something like this at the start of construct_object:

if self.is_instance_based():
    constructors = self._yaml_constructors
    multi_constructors = self._yaml_multi_constructors
else:
    constructors = self.yaml_constructors
    multi_constructors = self.yaml_multi_constructors

Then later code doesn't need to be duplicated

[Thom1729]

Should be TypeError.

[Thom1729]

Should be TypeError.

[perlpunk]

One thing which is not clear from the example is an important design question:
The current PR looks into the instance based constructors (if it is an instance), and if it doesn't find the tag there, it goes on to search in the class based constructors.
Meaning, doing

l1 = yaml.SafeLoader()
yaml.add_constructor('!dice', dice_constructor, Loader=yaml.SafeLoader)

will still result in finding a constructor for !dice when using l1

My proposal would be to only lookup in one or the other - either instance or class based.
After all we want to get away from the class based global-like thing, and any new stuff would only be supported by the instance API.

[ingydotnet]

One thing which is not clear from the example is an important design question:
The current PR looks into the instance based constructors (if it is an instance), and if it doesn't find the tag there, it goes on to search in the class based constructors.
Meaning, doing

l1 = yaml.SafeLoader()
yaml.add_constructor('!dice', dice_constructor, Loader=yaml.SafeLoader)

will still result in finding a constructor for !dice when using l1

My proposal would be to only lookup in one or the other - either instance or class based.
After all we want to get away from the class based global-like thing, and any new stuff would only be supported by the instance API.

Good point but your instance needs to at least copy over the default class constructors. iow, integers still need to work.

I still have a lot to finish up on this PR. Should have something reviewable by Monday.

[perlpunk]

Good point but your instance needs to at least copy over the default class constructors.

of course.

iow, integers still need to work.

integers?