Source code for boltons.funcutils

# -*- coding: utf-8 -*-
"""Python's built-in :mod:`functools` module builds several useful
utilities on top of Python's first-class function
support. ``funcutils`` generally stays in the same vein, adding to and
correcting Python's standard metaprogramming facilities.
from __future__ import print_function

import sys
import re
import inspect
import functools
import itertools
from types import MethodType, FunctionType

    make_method = MethodType
except NameError:
    # Python 3
    make_method = lambda desc, obj, obj_type: MethodType(desc, obj)
    basestring = (str, bytes)  # Python 3 compat
    _IS_PY2 = False
    _IS_PY2 = True

def get_module_callables(mod, ignore=None):
    """Returns two maps of (*types*, *funcs*) from *mod*, optionally
    ignoring based on the :class:`bool` return value of the *ignore*
    callable. *mod* can be a string name of a module in
    :data:`sys.modules` or the module instance itself.
    if isinstance(mod, basestring):
        mod = sys.modules[mod]
    types, funcs = {}, {}
    for attr_name in dir(mod):
        if ignore and ignore(attr_name):
            attr = getattr(mod, attr_name)
        except Exception:
            attr_mod_name = attr.__module__
        except AttributeError:
        if attr_mod_name != mod.__name__:
        if isinstance(attr, type):
            types[attr_name] = attr
        elif callable(attr):
            funcs[attr_name] = attr
    return types, funcs

[docs]def mro_items(type_obj): """Takes a type and returns an iterator over all class variables throughout the type hierarchy (respecting the MRO). >>> sorted(set([k for k, v in mro_items(int) if not k.startswith('__') and 'bytes' not in k and not callable(v)])) ['denominator', 'imag', 'numerator', 'real'] """ # TODO: handle slots? return itertools.chain.from_iterable(ct.__dict__.items() for ct in type_obj.__mro__)
[docs]def dir_dict(obj, raise_exc=False): """Return a dictionary of attribute names to values for a given object. Unlike ``obj.__dict__``, this function returns all attributes on the object, including ones on parent classes. """ # TODO: separate function for handling descriptors on types? ret = {} for k in dir(obj): try: ret[k] = getattr(obj, k) except Exception: if raise_exc: raise return ret
[docs]def copy_function(orig, copy_dict=True): """Returns a shallow copy of the function, including code object, globals, closure, etc. >>> func = lambda: func >>> func() is func True >>> func_copy = copy_function(func) >>> func_copy() is func True >>> func_copy is not func True Args: orig (function): The function to be copied. Must be a function, not just any method or callable. copy_dict (bool): Also copy any attributes set on the function instance. Defaults to ``True``. """ ret = FunctionType(orig.__code__, orig.__globals__, name=orig.__name__, argdefs=getattr(orig, "__defaults__", None), closure=getattr(orig, "__closure__", None)) if copy_dict: ret.__dict__.update(orig.__dict__) return ret
def partial_ordering(cls): """Class decorator, similar to :func:`functools.total_ordering`, except it is used to define `partial orderings`_ (i.e., it is possible that *x* is neither greater than, equal to, or less than *y*). It assumes the presence of the ``__le__()`` and ``__ge__()`` method, but nothing else. It will not override any existing additional comparison methods. .. _partial orderings: >>> @partial_ordering ... class MySet(set): ... def __le__(self, other): ... return self.issubset(other) ... def __ge__(self, other): ... return self.issuperset(other) ... >>> a = MySet([1,2,3]) >>> b = MySet([1,2]) >>> c = MySet([1,2,4]) >>> b < a True >>> b > a False >>> b < c True >>> a < c False >>> c > a False """ def __lt__(self, other): return self <= other and not self >= other def __gt__(self, other): return self >= other and not self <= other def __eq__(self, other): return self >= other and self <= other if not hasattr(cls, '__lt__'): cls.__lt__ = __lt__ if not hasattr(cls, '__gt__'): cls.__gt__ = __gt__ if not hasattr(cls, '__eq__'): cls.__eq__ = __eq__ return cls
[docs]class InstancePartial(functools.partial): """:class:`functools.partial` is a huge convenience for anyone working with Python's great first-class functions. It allows developers to curry arguments and incrementally create simpler callables for a variety of use cases. Unfortunately there's one big gap in its usefulness: methods. Partials just don't get bound as methods and automatically handed a reference to ``self``. The ``InstancePartial`` type remedies this by inheriting from :class:`functools.partial` and implementing the necessary descriptor protocol. There are no other differences in implementation or usage. :class:`CachedInstancePartial`, below, has the same ability, but is slightly more efficient. """ def __get__(self, obj, obj_type): return make_method(self, obj, obj_type)
[docs]class CachedInstancePartial(functools.partial): """The ``CachedInstancePartial`` is virtually the same as :class:`InstancePartial`, adding support for method-usage to :class:`functools.partial`, except that upon first access, it caches the bound method on the associated object, speeding it up for future accesses, and bringing the method call overhead to about the same as non-``partial`` methods. See the :class:`InstancePartial` docstring for more details. """ def __get__(self, obj, obj_type): # These assignments could've been in __init__, but there was # no simple way to do it without breaking one of PyPy or Py3. self.__name__ = None self.__doc__ = self.func.__doc__ self.__module__ = self.func.__module__ name = self.__name__ if name is None: for k, v in mro_items(obj_type): if v is self: self.__name__ = name = k if obj is None: return make_method(self, obj, obj_type) try: # since this is a data descriptor, this block # is probably only hit once (per object) return obj.__dict__[name] except KeyError: obj.__dict__[name] = ret = make_method(self, obj, obj_type) return ret
partial = CachedInstancePartial # # # # # # Function builder # # #
[docs]def wraps(func, injected=None, **kw): """Modeled after the built-in :func:`functools.wraps`, this function is used to make your decorator's wrapper functions reflect the wrapped function's: * Name * Documentation * Module * Signature The built-in :func:`functools.wraps` copies the first three, but does not copy the signature. This version of ``wraps`` can copy the inner function's signature exactly, allowing seamless usage and :mod:`introspection <inspect>`. Usage is identical to the built-in version:: >>> from boltons.funcutils import wraps >>> >>> def print_return(func): ... @wraps(func) ... def wrapper(*args, **kwargs): ... ret = func(*args, **kwargs) ... print(ret) ... return ret ... return wrapper ... >>> @print_return ... def example(): ... '''docstring''' ... return 'example return value' >>> >>> val = example() example return value >>> example.__name__ 'example' >>> example.__doc__ 'docstring' In addition, the boltons version of wraps supports modifying the outer signature based on the inner signature. By passing a list of *injected* argument names, those arguments will be removed from the outer wrapper's signature, allowing your decorator to provide arguments that aren't passed in. Args: func (function): The callable whose attributes are to be copied. injected (list): An optional list of argument names which should not appear in the new wrapper's signature. update_dict (bool): Whether to copy other, non-standard attributes of *func* over to the wrapper. Defaults to True. inject_to_varkw (bool): Ignore missing arguments when a ``**kwargs``-type catch-all is present. Defaults to True. For more in-depth wrapping of functions, see the :class:`FunctionBuilder` type, on which wraps was built. """ # TODO: maybe automatically use normal wraps in the very rare case # that the signatures actually match and no adapter is needed. if injected is None: injected = [] elif isinstance(injected, basestring): injected = [injected] else: injected = list(injected) if isinstance(func, (classmethod, staticmethod)): raise TypeError('wraps does not support wrapping classmethods and' ' staticmethods, change the order of wrapping to' ' wrap the underlying function: %r' % (getattr(func, '__func__', None),)) update_dict = kw.pop('update_dict', True) inject_to_varkw = kw.pop('inject_to_varkw', True) if kw: raise TypeError('unexpected kwargs: %r' % kw.keys()) fb = FunctionBuilder.from_func(func) for arg in injected: try: fb.remove_arg(arg) except MissingArgument: if inject_to_varkw and fb.varkw is not None: continue # keyword arg will be caught by the varkw raise fb.body = 'return _call(%s)' % fb.get_invocation_str() def wrapper_wrapper(wrapper_func): execdict = dict(_call=wrapper_func, _func=func) fully_wrapped = fb.get_func(execdict, with_dict=update_dict) fully_wrapped.__wrapped__ = func # ref to the original function (#115) return fully_wrapped return wrapper_wrapper
[docs]class FunctionBuilder(object): """The FunctionBuilder type provides an interface for programmatically creating new functions, either based on existing functions or from scratch. Values are passed in at construction or set as attributes on the instance. For creating a new function based of an existing one, see the :meth:`~FunctionBuilder.from_func` classmethod. At any point, :meth:`~FunctionBuilder.get_func` can be called to get a newly compiled function, based on the values configured. >>> fb = FunctionBuilder('return_five', doc='returns the integer 5', ... body='return 5') >>> f = fb.get_func() >>> f() 5 >>> fb.varkw = 'kw' >>> f_kw = fb.get_func() >>> f_kw(ignored_arg='ignored_val') 5 Note that function signatures themselves changed quite a bit in Python 3, so several arguments are only applicable to FunctionBuilder in Python 3. Except for *name*, all arguments to the constructor are keyword arguments. Args: name (str): Name of the function. doc (str): `Docstring`_ for the function, defaults to empty. module (str): Name of the module from which this function was imported. Defaults to None. body (str): String version of the code representing the body of the function. Defaults to ``'pass'``, which will result in a function which does nothing and returns ``None``. args (list): List of argument names, defaults to empty list, denoting no arguments. varargs (str): Name of the catch-all variable for positional arguments. E.g., "args" if the resultant function is to have ``*args`` in the signature. Defaults to None. varkw (str): Name of the catch-all variable for keyword arguments. E.g., "kwargs" if the resultant function is to have ``**kwargs`` in the signature. Defaults to None. defaults (dict): A mapping of argument names to default values. kwonlyargs (list): Argument names which are only valid as keyword arguments. **Python 3 only.** kwonlydefaults (dict): A mapping, same as normal *defaults*, but only for the *kwonlyargs*. **Python 3 only.** annotations (dict): Mapping of type hints and so forth. **Python 3 only.** filename (str): The filename that will appear in tracebacks. Defaults to "boltons.funcutils.FunctionBuilder". indent (int): Number of spaces with which to indent the function *body*. Values less than 1 will result in an error. dict (dict): Any other attributes which should be added to the functions compiled with this FunctionBuilder. All of these arguments are also made available as attributes which can be mutated as necessary. .. _Docstring: """ if _IS_PY2: _argspec_defaults = {'args': list, 'varargs': lambda: None, 'varkw': lambda: None, 'defaults': lambda: None} @classmethod def _argspec_to_dict(cls, f): args, varargs, varkw, defaults = inspect.getargspec(f) return {'args': args, 'varargs': varargs, 'varkw': varkw, 'defaults': defaults} else: _argspec_defaults = {'args': list, 'varargs': lambda: None, 'varkw': lambda: None, 'defaults': lambda: None, 'kwonlyargs': list, 'kwonlydefaults': dict, 'annotations': dict} @classmethod def _argspec_to_dict(cls, f): argspec = inspect.getfullargspec(f) return dict((attr, getattr(argspec, attr)) for attr in cls._argspec_defaults) _defaults = {'doc': str, 'dict': dict, 'module': lambda: None, 'body': lambda: 'pass', 'indent': lambda: 4, 'filename': lambda: 'boltons.funcutils.FunctionBuilder'} _defaults.update(_argspec_defaults) _compile_count = itertools.count() def __init__(self, name, **kw): = name for a, default_factory in self._defaults.items(): val = kw.pop(a, None) if val is None: val = default_factory() setattr(self, a, val) if kw: raise TypeError('unexpected kwargs: %r' % kw.keys()) return # def get_argspec(self): # TODO if _IS_PY2: def get_sig_str(self): return inspect.formatargspec(self.args, self.varargs, self.varkw, []) def get_invocation_str(self): return inspect.formatargspec(self.args, self.varargs, self.varkw, [])[1:-1] else: def get_sig_str(self): return inspect.formatargspec(self.args, self.varargs, self.varkw, [], self.kwonlyargs, {}, self.annotations) _KWONLY_MARKER = re.compile(r""" \* # a star \s* # followed by any amount of whitespace , # followed by a comma \s* # followed by any amount of whitespace """, re.VERBOSE) def get_invocation_str(self): kwonly_pairs = None formatters = {} if self.kwonlyargs: kwonly_pairs = dict((arg, arg) for arg in self.kwonlyargs) formatters['formatvalue'] = lambda value: '=' + value sig = inspect.formatargspec(self.args, self.varargs, self.varkw, [], kwonly_pairs, kwonly_pairs, {}, **formatters) sig = self._KWONLY_MARKER.sub('', sig) return sig[1:-1]
[docs] @classmethod def from_func(cls, func): """Create a new FunctionBuilder instance based on an existing function. The original function will not be stored or modified. """ # TODO: copy_body? gonna need a good signature regex. # TODO: might worry about __closure__? if not callable(func): raise TypeError('expected callable object, not %r' % (func,)) kwargs = {'name': func.__name__, 'doc': func.__doc__, 'module': func.__module__, 'dict': getattr(func, '__dict__', {})} kwargs.update(cls._argspec_to_dict(func)) return cls(**kwargs)
[docs] def get_func(self, execdict=None, add_source=True, with_dict=True): """Compile and return a new function based on the current values of the FunctionBuilder. Args: execdict (dict): The dictionary representing the scope in which the compilation should take place. Defaults to an empty dict. add_source (bool): Whether to add the source used to a special ``__source__`` attribute on the resulting function. Defaults to True. with_dict (bool): Add any custom attributes, if applicable. Defaults to True. To see an example of usage, see the implementation of :func:`~boltons.funcutils.wraps`. """ execdict = execdict or {} body = self.body or self._default_body tmpl = 'def {name}{sig_str}:' tmpl += '\n{body}' body = _indent(self.body, ' ' * self.indent) name ='<', '_').replace('>', '_') # lambdas src = tmpl.format(name=name, sig_str=self.get_sig_str(), doc=self.doc, body=body) self._compile(src, execdict) func = execdict[name] func.__name__ = func.__doc__ = self.doc func.__defaults__ = self.defaults if not _IS_PY2: func.__kwdefaults__ = self.kwonlydefaults if with_dict: func.__dict__.update(self.dict) func.__module__ = self.module # TODO: caller module fallback? if add_source: func.__source__ = src return func
[docs] def get_defaults_dict(self): """Get a dictionary of function arguments with defaults and the respective values. """ ret = dict(reversed(list(zip(reversed(self.args), reversed(self.defaults or []))))) return ret
[docs] def remove_arg(self, arg_name): """Remove an argument from this FunctionBuilder's argument list. The resulting function will have one less argument per call to this function. Args: arg_name (str): The name of the argument to remove. Raises a :exc:`ValueError` if the argument is not present. """ args = self.args d_dict = self.get_defaults_dict() try: args.remove(arg_name) except ValueError: try: self.kwonlyargs.remove(arg_name) except (AttributeError, ValueError): # py2, or py3 and missing from both exc = MissingArgument('arg %r not found in %s argument list:' ' %r' % (arg_name,, args)) exc.arg_name = arg_name raise exc else: self.kwonlydefaults.pop(arg_name, None) else: d_dict.pop(arg_name, None) self.defaults = tuple([d_dict[a] for a in args if a in d_dict]) return
def _compile(self, src, execdict): filename = ('<%s-%d>' % (self.filename, next(self._compile_count),)) try: code = compile(src, filename, 'single') exec(code, execdict) except Exception: raise return execdict
class MissingArgument(ValueError): pass def _indent(text, margin, newline='\n', key=bool): "based on boltons.strutils.indent" indented_lines = [(margin + line if key(line) else line) for line in text.splitlines()] return newline.join(indented_lines) try: from functools import total_ordering # 2.7+ except ImportError: # python 2.6 def total_ordering(cls): """Class decorator that fills in missing comparators/ordering methods. Backport of :func:`functools.total_ordering` to work with Python 2.6. Code from """ convert = { '__lt__': [ ('__gt__', lambda self, other: not (self < other or self == other)), ('__le__', lambda self, other: self < other or self == other), ('__ge__', lambda self, other: not self < other)], '__le__': [ ('__ge__', lambda self, other: not self <= other or self == other), ('__lt__', lambda self, other: self <= other and not self == other), ('__gt__', lambda self, other: not self <= other)], '__gt__': [ ('__lt__', lambda self, other: not (self > other or self == other)), ('__ge__', lambda self, other: self > other or self == other), ('__le__', lambda self, other: not self > other)], '__ge__': [ ('__le__', lambda self, other: (not self >= other) or self == other), ('__gt__', lambda self, other: self >= other and not self == other), ('__lt__', lambda self, other: not self >= other)] } roots = set(dir(cls)) & set(convert) if not roots: raise ValueError('must define at least one ordering operation:' ' < > <= >=') root = max(roots) # prefer __lt__ to __le__ to __gt__ to __ge__ for opname, opfunc in convert[root]: if opname not in roots: opfunc.__name__ = opname opfunc.__doc__ = getattr(int, opname).__doc__ setattr(cls, opname, opfunc) return cls # end