Source code for bokeh.util.future

''' Utilities for Py2/Py3 interop.


import sys

[docs]def with_metaclass(meta, *bases): """ Add metaclasses in both Python 2 and Python 3. Function from jinja2/ License: BSD. Use it like this:: class BaseForm(object): pass class FormType(type): pass class Form(with_metaclass(FormType, BaseForm)): pass This requires a bit of explanation: the basic idea is to make a dummy metaclass for one level of class instantiation that replaces itself with the actual metaclass. Because of internal type checks we also need to make sure that we downgrade the custom metaclass for one level to something closer to type (that's why __call__ and __init__ comes back from type etc.). This has the advantage over six.with_metaclass of not introducing dummy classes into the final MRO. """ class metaclass(meta): __call__ = type.__call__ __init__ = type.__init__ def __new__(cls, name, this_bases, d): if this_bases is None: return type.__new__(cls, name, (), d) return meta(name, bases, d) return metaclass('temporary_class', None, {})
# There is a problem with using @wraps decorator in combination with functools.partial. # This issue is not present in Python 3. # This redefinition will be triggered only if issue affects user, # otherwise regular definition of @wraps will be used. # # this code snippet was originally posted in following stack overflow discussion: # from functools import wraps, partial, WRAPPER_ASSIGNMENTS try: wraps(partial(wraps))(wraps) except AttributeError: @wraps(wraps) def wraps(obj, attr_names=WRAPPER_ASSIGNMENTS, wraps=wraps): return wraps(obj, assigned=(name for name in attr_names if hasattr(obj, name))) del partial, WRAPPER_ASSIGNMENTS # inspect.getargspec and inspect.formatargspec were deprecated in Python 3.5 # in favor of the newer inspect.signature introspection if sys.version_info[:2] < (3, 4): def signature(func): # The modifications in this function are to make results more in line # with Python 3, i.e. self is not included in bound methods, supplied # parameters are not reported in partial, etc. This simplifies the # downstream code considerably. from inspect import getargspec, isfunction, ismethod from functools import partial if isfunction(func) or ismethod(func): sig = getargspec(func) if ismethod(func): sig.args.remove('self') return sig elif isinstance(func, partial): sig = getargspec(func.func) if 'self' in sig.args: sig.args.remove('self') for name in func.keywords.keys(): sig.args.remove(name) for val in func.args: del sig.args[0] return sig else: sig = getargspec(func.__call__) sig.args.remove('self') return sig def format_signature(sig): from inspect import formatargspec return formatargspec(*sig) def get_param_info(sig): return (sig.args, sig.defaults or []) else: from inspect import signature; signature def format_signature(sig): return str(sig) def get_param_info(sig): defaults = [] for param in sig.parameters.values(): if param.default is not param.empty: defaults.append(param.default) return list(sig.parameters), defaults