def __classcall_private__(cls, base_ring, dispatch=True):
r"""
Implement the dispatching of ``Modules(field)`` to
``VectorSpaces(field)``.
This feature will later be extended, probably as a covariant
functorial construction, to support modules over various kinds
of rings (principal ideal domains, ...), or even over semirings.
TESTS::
sage: C = Modules(ZZ); C
Category of modules over Integer Ring
sage: C is Modules(ZZ, dispatch = False)
True
sage: C is Modules(ZZ, dispatch = True)
True
sage: C._reduction
(<class 'sage.categories.modules.Modules'>, (Integer Ring,), {'dispatch': False})
sage: TestSuite(C).run()
sage: Modules(QQ) is VectorSpaces(QQ)
True
sage: Modules(QQ, dispatch = True) is VectorSpaces(QQ)
True
sage: C = Modules(NonNegativeIntegers()); C # todo: not implemented
Category of semiring modules over Non negative integers
sage: C = Modules(QQ, dispatch = False); C
Category of modules over Rational Field
sage: C._reduction
(<class 'sage.categories.modules.Modules'>, (Rational Field,), {'dispatch': False})
sage: TestSuite(C).run()
"""
if dispatch:
if base_ring in _Fields or (isinstance(base_ring, Category)
and base_ring.is_subcategory(_Fields)):
from vector_spaces import VectorSpaces
return VectorSpaces(base_ring, check=False)
result = super(Modules, cls).__classcall__(cls, base_ring)
result._reduction[2]['dispatch'] = False
return result
def __classcall_private__(cls, base_ring, dispatch = True):
"""
This method implements the default behavior of dispatching
``Modules(field)`` to ``VectorSpaces(field)``. This feature
will later be extended to modules over a principal ideal
domain/ring or over a semiring.
TESTS::
sage: C = Modules(ZZ); C
Category of modules over Integer Ring
sage: C is Modules(ZZ, dispatch = False)
True
sage: C is Modules(ZZ, dispatch = True)
True
sage: C._reduction
(<class 'sage.categories.modules.Modules'>, (Integer Ring,), {'dispatch': False})
sage: TestSuite(C).run()
sage: Modules(QQ) is VectorSpaces(QQ)
True
sage: Modules(QQ, dispatch = True) is VectorSpaces(QQ)
True
sage: C = Modules(NonNegativeIntegers()); C # todo: not implemented
Category of semiring modules over Non negative integers
sage: C = Modules(QQ, dispatch = False); C
Category of modules over Rational Field
sage: C._reduction
(<class 'sage.categories.modules.Modules'>, (Rational Field,), {'dispatch': False})
sage: TestSuite(C).run()
"""
if dispatch:
if base_ring in _Fields:
return VectorSpaces(base_ring, check=False)
result = super(Modules, cls).__classcall__(cls, base_ring)
result._reduction[2]['dispatch'] = False
return result