def as_interface(obj, cls=None, methods=None, required=None):
"""Ensure basic interface compliance for an instance or dict of callables.
Checks that ``obj`` implements public methods of ``cls`` or has members
listed in ``methods``. If ``required`` is not supplied, implementing at
least one interface method is sufficient. Methods present on ``obj`` that
are not in the interface are ignored.
If ``obj`` is a dict and ``dict`` does not meet the interface
requirements, the keys of the dictionary are inspected. Keys present in
``obj`` that are not in the interface will raise TypeErrors.
Raises TypeError if ``obj`` does not meet the interface criteria.
In all passing cases, an object with callable members is returned. In the
simple case, ``obj`` is returned as-is; if dict processing kicks in then
an anonymous class is returned.
obj
A type, instance, or dictionary of callables.
cls
Optional, a type. All public methods of cls are considered the
interface. An ``obj`` instance of cls will always pass, ignoring
``required``..
methods
Optional, a sequence of method names to consider as the interface.
required
Optional, a sequence of mandatory implementations. If omitted, an
``obj`` that provides at least one interface method is considered
sufficient. As a convenience, required may be a type, in which case
all public methods of the type are required.
"""
if not cls and not methods:
raise TypeError('a class or collection of method names are required')
if isinstance(cls, type) and isinstance(obj, cls):
return obj
interface = set(methods or [m for m in dir(cls) if not m.startswith('_')])
implemented = set(dir(obj))
complies = operator.ge
if isinstance(required, type):
required = interface
elif not required:
required = set()
complies = operator.gt
else:
required = set(required)
if complies(implemented.intersection(interface), required):
return obj
# No dict duck typing here.
if not type(obj) is dict:
qualifier = complies is operator.gt and 'any of' or 'all of'
raise TypeError("%r does not implement %s: %s" %
(obj, qualifier, ', '.join(interface)))
class AnonymousInterface(object):
"""A callable-holding shell."""
if cls:
AnonymousInterface.__name__ = 'Anonymous' + cls.__name__
found = set()
for method, impl in dictlike_iteritems(obj):
if method not in interface:
raise TypeError("%r: unknown in this interface" % method)
if not callable(impl):
raise TypeError("%r=%r is not callable" % (method, impl))
setattr(AnonymousInterface, method, staticmethod(impl))
found.add(method)
if complies(found, required):
return AnonymousInterface
raise TypeError("dictionary does not contain required keys %s" %
', '.join(required - found))
def as_interface(obj, cls=None, methods=None, required=None):
"""Ensure basic interface compliance for an instance or dict of callables.
Checks that ``obj`` implements public methods of ``cls`` or has members
listed in ``methods``. If ``required`` is not supplied, implementing at
least one interface method is sufficient. Methods present on ``obj`` that
are not in the interface are ignored.
If ``obj`` is a dict and ``dict`` does not meet the interface
requirements, the keys of the dictionary are inspected. Keys present in
``obj`` that are not in the interface will raise TypeErrors.
Raises TypeError if ``obj`` does not meet the interface criteria.
In all passing cases, an object with callable members is returned. In the
simple case, ``obj`` is returned as-is; if dict processing kicks in then
an anonymous class is returned.
obj
A type, instance, or dictionary of callables.
cls
Optional, a type. All public methods of cls are considered the
interface. An ``obj`` instance of cls will always pass, ignoring
``required``..
methods
Optional, a sequence of method names to consider as the interface.
required
Optional, a sequence of mandatory implementations. If omitted, an
``obj`` that provides at least one interface method is considered
sufficient. As a convenience, required may be a type, in which case
all public methods of the type are required.
"""
if not cls and not methods:
raise TypeError('a class or collection of method names are required')
if isinstance(cls, type) and isinstance(obj, cls):
return obj
interface = set(methods or [m for m in dir(cls) if not m.startswith('_')])
implemented = set(dir(obj))
complies = operator.ge
if isinstance(required, type):
required = interface
elif not required:
required = set()
complies = operator.gt
else:
required = set(required)
if complies(implemented.intersection(interface), required):
return obj
# No dict duck typing here.
if not type(obj) is dict:
qualifier = complies is operator.gt and 'any of' or 'all of'
raise TypeError("%r does not implement %s: %s" % (
obj, qualifier, ', '.join(interface)))
class AnonymousInterface(object):
"""A callable-holding shell."""
if cls:
AnonymousInterface.__name__ = 'Anonymous' + cls.__name__
found = set()
for method, impl in dictlike_iteritems(obj):
if method not in interface:
raise TypeError("%r: unknown in this interface" % method)
if not callable(impl):
raise TypeError("%r=%r is not callable" % (method, impl))
setattr(AnonymousInterface, method, staticmethod(impl))
found.add(method)
if complies(found, required):
return AnonymousInterface
raise TypeError("dictionary does not contain required keys %s" %
', '.join(required - found))
def format_argspec_plus(fn, grouped=True):
"""Returns a dictionary of formatted, introspected function arguments.
A enhanced variant of inspect.formatargspec to support code generation.
fn
An inspectable callable or tuple of inspect getargspec() results.
grouped
Defaults to True; include (parens, around, argument) lists
Returns:
args
Full inspect.formatargspec for fn
self_arg
The name of the first positional argument, varargs[0], or None
if the function defines no positional arguments.
apply_pos
args, re-written in calling rather than receiving syntax. Arguments are
passed positionally.
apply_kw
Like apply_pos, except keyword-ish args are passed as keywords.
Example::
>>> format_argspec_plus(lambda self, a, b, c=3, **d: 123)
{'args': '(self, a, b, c=3, **d)',
'self_arg': 'self',
'apply_kw': '(self, a, b, c=c, **d)',
'apply_pos': '(self, a, b, c, **d)'}
"""
if callable(fn):
spec = inspect_getfullargspec(fn)
else:
# we accept an existing argspec...
spec = fn
args = inspect.formatargspec(*spec)
if spec[0]:
self_arg = spec[0][0]
elif spec[1]:
self_arg = '%s[0]' % spec[1]
else:
self_arg = None
# Py3K
#apply_pos = inspect.formatargspec(spec[0], spec[1], spec[2], None, spec[4])
#num_defaults = 0
#if spec[3]:
# num_defaults += len(spec[3])
#if spec[4]:
# num_defaults += len(spec[4])
#name_args = spec[0] + spec[4]
# Py2K
apply_pos = inspect.formatargspec(spec[0], spec[1], spec[2])
num_defaults = 0
if spec[3]:
num_defaults += len(spec[3])
name_args = spec[0]
# end Py2K
if num_defaults:
defaulted_vals = name_args[0 - num_defaults:]
else:
defaulted_vals = ()
apply_kw = inspect.formatargspec(name_args,
spec[1],
spec[2],
defaulted_vals,
formatvalue=lambda x: '=' + x)
if grouped:
return dict(args=args,
self_arg=self_arg,
apply_pos=apply_pos,
apply_kw=apply_kw)
else:
return dict(args=args[1:-1],
self_arg=self_arg,
apply_pos=apply_pos[1:-1],
apply_kw=apply_kw[1:-1])
def format_argspec_plus(fn, grouped=True):
"""Returns a dictionary of formatted, introspected function arguments.
A enhanced variant of inspect.formatargspec to support code generation.
fn
An inspectable callable or tuple of inspect getargspec() results.
grouped
Defaults to True; include (parens, around, argument) lists
Returns:
args
Full inspect.formatargspec for fn
self_arg
The name of the first positional argument, varargs[0], or None
if the function defines no positional arguments.
apply_pos
args, re-written in calling rather than receiving syntax. Arguments are
passed positionally.
apply_kw
Like apply_pos, except keyword-ish args are passed as keywords.
Example::
>>> format_argspec_plus(lambda self, a, b, c=3, **d: 123)
{'args': '(self, a, b, c=3, **d)',
'self_arg': 'self',
'apply_kw': '(self, a, b, c=c, **d)',
'apply_pos': '(self, a, b, c, **d)'}
"""
if callable(fn):
spec = inspect_getfullargspec(fn)
else:
# we accept an existing argspec...
spec = fn
args = inspect.formatargspec(*spec)
if spec[0]:
self_arg = spec[0][0]
elif spec[1]:
self_arg = '%s[0]' % spec[1]
else:
self_arg = None
# Py3K
#apply_pos = inspect.formatargspec(spec[0], spec[1], spec[2], None, spec[4])
#num_defaults = 0
#if spec[3]:
# num_defaults += len(spec[3])
#if spec[4]:
# num_defaults += len(spec[4])
#name_args = spec[0] + spec[4]
# Py2K
apply_pos = inspect.formatargspec(spec[0], spec[1], spec[2])
num_defaults = 0
if spec[3]:
num_defaults += len(spec[3])
name_args = spec[0]
# end Py2K
if num_defaults:
defaulted_vals = name_args[0-num_defaults:]
else:
defaulted_vals = ()
apply_kw = inspect.formatargspec(name_args, spec[1], spec[2], defaulted_vals,
formatvalue=lambda x: '=' + x)
if grouped:
return dict(args=args, self_arg=self_arg,
apply_pos=apply_pos, apply_kw=apply_kw)
else:
return dict(args=args[1:-1], self_arg=self_arg,
apply_pos=apply_pos[1:-1], apply_kw=apply_kw[1:-1])
