comparison mercurial/thirdparty/zope/interface/declarations.py @ 37208:b9dd8403d8ff

zope: force module import by importing symbols

Previously, we tried to import a module and handle the ImportError.
Our lazy module importer doesn't verify the module exists and returns
a dummy object representing the module. Only once we attempt to load
a symbol in the module does the ImportError get raises.

This means that simple imports inside `try..except ImportError` don't
detect missing modules.

This commit changes imports in zope.interface to access symbols, thus
forcing module load and triggering ImportError.

This fixes zope.interface for pure builds.

Differential Revision: https://phab.mercurial-scm.org/D2980

37207:d3f1d3e4e58d

ClassProvidesBasePy = ClassProvidesBaseFallback # BBB
ClassProvidesBase = ClassProvidesBaseFallback

# Try to get C base:
try:
    from . import _zope_interface_coptimizations
except ImportError:
    pass
else:
    from ._zope_interface_coptimizations import ClassProvidesBase


class ClassProvides(Declaration, ClassProvidesBase):
    """Special descriptor for class __provides__

    The descriptor caches the implementedBy info, so that

    return output

_empty = Declaration()

try:
    from . import _zope_interface_coptimizations
except ImportError:
    pass
else:
    from ._zope_interface_coptimizations import implementedBy
    from ._zope_interface_coptimizations import providedBy
    from ._zope_interface_coptimizations import (
        getObjectSpecification)
    from ._zope_interface_coptimizations import (
        ObjectSpecificationDescriptor)

objectSpecificationDescriptor = ObjectSpecificationDescriptor()

37208:b9dd8403d8ff

ClassProvidesBasePy = ClassProvidesBaseFallback # BBB
ClassProvidesBase = ClassProvidesBaseFallback

# Try to get C base:
try:
    from ._zope_interface_coptimizations import ClassProvidesBase
except ImportError:
    pass

class ClassProvides(Declaration, ClassProvidesBase):
    """Special descriptor for class __provides__

    The descriptor caches the implementedBy info, so that

    return output

_empty = Declaration()

try:
    from ._zope_interface_coptimizations import (
        getObjectSpecification,
        implementedBy,
        ObjectSpecificationDescriptor,
        providedBy,
    )
except ImportError:
    pass

objectSpecificationDescriptor = ObjectSpecificationDescriptor()