Should dump_schema be an instance method of a schema?

[fuhrysteve]

We may want to avoid imposing a BaseJsonSchema (unless we use mixins, which also seem like something we should avoid unless there are compelling reasons to) since Marhmallow-sqlalchemy uses them and this library needs to be compatible with that library.

However, I'm struggling to think of another way to inject this functionality into marshmallow without doing something funky like monkey patching.

Maybe we could suggest a metaclass sort of plugin system in marshmallow?

Mixin style

from marshmallow_sqlalchemy import ModelSchema
from marshmallow_jsonschema import JSONSchemaMixin
from .models import Book  # some sqlalchemy model

class BookSchema(ModelSchema, JSONSchemaMixin):
    class Meta:
        model = Book

bs = BookSchema()
bs.jsonschema()

Metaclass "plugin" style

from marshmallow import register_plugin  # this doesn't actually exist
from marshmallow_jsonschema import JSONSchemaPlugin
register_plugin(JSONSchemaPlugin)

from marshmallow_sqlalchemy import ModelSchema
from .models import Book  # some sqlalchemy model

class BookSchema(ModelSchema):
    plugins = ['jsonschema']
    class Meta:
        model = Book

bs = BookSchema()
bs.jsonschema()