boltons.funcutils 源代码

# Copyright (c) 2013, Mahmoud Hashemi
# Redistribution and use in source and binary forms, with or without
# modification, are permitted provided that the following conditions are
# met:
#    * Redistributions of source code must retain the above copyright
#      notice, this list of conditions and the following disclaimer.
#    * Redistributions in binary form must reproduce the above
#      copyright notice, this list of conditions and the following
#      disclaimer in the documentation and/or other materials provided
#      with the distribution.
#    * The names of the contributors may not be used to endorse or
#      promote products derived from this software without specific
#      prior written permission.

"""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.

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

make_method = lambda desc, obj, obj_type: MethodType(desc, obj)

    from .typeutils import make_sentinel
    NO_DEFAULT = make_sentinel(var_name='NO_DEFAULT')
except ImportError:
    NO_DEFAULT = object()

def inspect_formatargspec(
        args, varargs=None, varkw=None, defaults=None,
        kwonlyargs=(), kwonlydefaults={}, annotations={},
        formatvarargs=lambda name: '*' + name,
        formatvarkw=lambda name: '**' + name,
        formatvalue=lambda value: '=' + repr(value),
        formatreturns=lambda text: ' -> ' + text,
    """Copy formatargspec from python 3.7 standard library.
    Python 3 has deprecated formatargspec and requested that Signature
    be used instead, however this requires a full reimplementation
    of formatargspec() in terms of creating Parameter objects and such.
    Instead of introducing all the object-creation overhead and having
    to reinvent from scratch, just copy their compatibility routine.

    def formatargandannotation(arg):
        result = formatarg(arg)
        if arg in annotations:
            result += ': ' + formatannotation(annotations[arg])
        return result
    specs = []
    if defaults:
        firstdefault = len(args) - len(defaults)
    for i, arg in enumerate(args):
        spec = formatargandannotation(arg)
        if defaults and i >= firstdefault:
            spec = spec + formatvalue(defaults[i - firstdefault])
    if varargs is not None:
        if kwonlyargs:
    if kwonlyargs:
        for kwonlyarg in kwonlyargs:
            spec = formatargandannotation(kwonlyarg)
            if kwonlydefaults and kwonlyarg in kwonlydefaults:
                spec += formatvalue(kwonlydefaults[kwonlyarg])
    if varkw is not None:
    result = '(' + ', '.join(specs) + ')'
    if 'return' in annotations:
        result += formatreturns(formatannotation(annotations['return']))
    return result

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, str):
        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

[文档] 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__)
[文档] 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
[文档] 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 hasattr(orig, "__kwdefaults__"): ret.__kwdefaults__ = orig.__kwdefaults__ 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
[文档] 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. """ @property def _partialmethod(self): return functools.partialmethod(self.func, *self.args, **self.keywords) def __get__(self, obj, obj_type): return make_method(self, obj, obj_type)
[文档] 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. """ @property def _partialmethod(self): return functools.partialmethod(self.func, *self.args, **self.keywords) def __set_name__(self, obj_type, name): self.__name__ = name 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__ = getattr(self, "__name__", None) self.__doc__ = self.func.__doc__ self.__module__ = self.func.__module__ name = self.__name__ 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
[文档] def format_invocation(name='', args=(), kwargs=None, **kw): """Given a name, positional arguments, and keyword arguments, format a basic Python-style function call. >>> print(format_invocation('func', args=(1, 2), kwargs={'c': 3})) func(1, 2, c=3) >>> print(format_invocation('a_func', args=(1,))) a_func(1) >>> print(format_invocation('kw_func', kwargs=[('a', 1), ('b', 2)])) kw_func(a=1, b=2) """ _repr = kw.pop('repr', repr) if kw: raise TypeError('unexpected keyword args: %r' % ', '.join(kw.keys())) kwargs = kwargs or {} a_text = ', '.join([_repr(a) for a in args]) if isinstance(kwargs, dict): kwarg_items = [(k, kwargs[k]) for k in sorted(kwargs)] else: kwarg_items = kwargs kw_text = ', '.join([f'{k}={_repr(v)}' for k, v in kwarg_items]) all_args_text = a_text if all_args_text and kw_text: all_args_text += ', ' all_args_text += kw_text return f'{name}({all_args_text})'
[文档] def format_exp_repr(obj, pos_names, req_names=None, opt_names=None, opt_key=None): """Render an expression-style repr of an object, based on attribute names, which are assumed to line up with arguments to an initializer. >>> class Flag(object): ... def __init__(self, length, width, depth=None): ... self.length = length ... self.width = width ... self.depth = depth ... That's our Flag object, here are some example reprs for it: >>> flag = Flag(5, 10) >>> print(format_exp_repr(flag, ['length', 'width'], [], ['depth'])) Flag(5, 10) >>> flag2 = Flag(5, 15, 2) >>> print(format_exp_repr(flag2, ['length'], ['width', 'depth'])) Flag(5, width=15, depth=2) By picking the pos_names, req_names, opt_names, and opt_key, you can fine-tune how you want the repr to look. Args: obj (object): The object whose type name will be used and attributes will be checked pos_names (list): Required list of attribute names which will be rendered as positional arguments in the output repr. req_names (list): List of attribute names which will always appear in the keyword arguments in the output repr. Defaults to None. opt_names (list): List of attribute names which may appear in the keyword arguments in the output repr, provided they pass the *opt_key* check. Defaults to None. opt_key (callable): A function or callable which checks whether an opt_name should be in the repr. Defaults to a ``None``-check. """ cn = type(obj).__name__ req_names = req_names or [] opt_names = opt_names or [] uniq_names, all_names = set(), [] for name in req_names + opt_names: if name in uniq_names: continue uniq_names.add(name) all_names.append(name) if opt_key is None: opt_key = lambda v: v is None assert callable(opt_key) args = [getattr(obj, name, None) for name in pos_names] kw_items = [(name, getattr(obj, name, None)) for name in all_names] kw_items = [(name, val) for name, val in kw_items if not (name in opt_names and opt_key(val))] return format_invocation(cn, args, kw_items)
[文档] def format_nonexp_repr(obj, req_names=None, opt_names=None, opt_key=None): """Format a non-expression-style repr Some object reprs look like object instantiation, e.g., App(r=[], mw=[]). This makes sense for smaller, lower-level objects whose state roundtrips. But a lot of objects contain values that don't roundtrip, like types and functions. For those objects, there is the non-expression style repr, which mimic's Python's default style to make a repr like so: >>> class Flag(object): ... def __init__(self, length, width, depth=None): ... self.length = length ... self.width = width ... self.depth = depth ... >>> flag = Flag(5, 10) >>> print(format_nonexp_repr(flag, ['length', 'width'], ['depth'])) <Flag length=5 width=10> If no attributes are specified or set, utilizes the id, not unlike Python's built-in behavior. >>> print(format_nonexp_repr(flag)) <Flag id=...> """ cn = obj.__class__.__name__ req_names = req_names or [] opt_names = opt_names or [] uniq_names, all_names = set(), [] for name in req_names + opt_names: if name in uniq_names: continue uniq_names.add(name) all_names.append(name) if opt_key is None: opt_key = lambda v: v is None assert callable(opt_key) items = [(name, getattr(obj, name, None)) for name in all_names] labels = [f'{name}={val!r}' for name, val in items if not (name in opt_names and opt_key(val))] if not labels: labels = ['id=%s' % id(obj)] ret = '<{} {}>'.format(cn, ' '.join(labels)) return ret
# # # # # # Function builder # # #
[文档] def wraps(func, injected=None, expected=None, **kw): """Decorator factory to apply update_wrapper() to a wrapper function. Modeled after built-in :func:`functools.wraps`. Returns a decorator that invokes update_wrapper() with the decorated function as the wrapper argument and the arguments to wraps() as the remaining arguments. Default arguments are as for update_wrapper(). This is a convenience function to simplify applying partial() to update_wrapper(). Same example as in update_wrapper's doc but with wraps: >>> 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' """ return partial(update_wrapper, func=func, build_from=None, injected=injected, expected=expected, **kw)
def update_wrapper(wrapper, func, injected=None, expected=None, build_from=None, **kw): """Modeled after the built-in :func:`functools.update_wrapper`, this function is used to make your wrapper function reflect the wrapped function's: * Name * Documentation * Module * Signature The built-in :func:`functools.update_wrapper` copies the first three, but does not copy the signature. This version of ``update_wrapper`` 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 update_wrapper >>> >>> def print_return(func): ... def wrapper(*args, **kwargs): ... ret = func(*args, **kwargs) ... print(ret) ... return ret ... return update_wrapper(wrapper, func) ... >>> @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 update_wrapper supports modifying the outer 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: wrapper (function) : The callable to which the attributes of *func* are to be copied. 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. expected (list): An optional list of argument names (or (name, default) pairs) representing new arguments introduced by the wrapper (the opposite of *injected*). See :meth:`FunctionBuilder.add_arg()` for more details. build_from (function): The callable from which the new wrapper is built. Defaults to *func*, unless *wrapper* is partial object built from *func*, in which case it defaults to *wrapper*. Useful in some specific cases where *wrapper* and *func* have the same arguments but differ on which are keyword-only and positional-only. 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. hide_wrapped (bool): Remove reference to the wrapped function(s) in the updated function. In opposition to the built-in :func:`functools.update_wrapper` bolton's version returns a copy of the function and does not modify anything in place. For more in-depth wrapping of functions, see the :class:`FunctionBuilder` type, on which update_wrapper was built. """ if injected is None: injected = [] elif isinstance(injected, str): injected = [injected] else: injected = list(injected) expected_items = _parse_wraps_expected(expected) 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) hide_wrapped = kw.pop('hide_wrapped', False) if kw: raise TypeError('unexpected kwargs: %r' % kw.keys()) if isinstance(wrapper, functools.partial) and func is wrapper.func: build_from = build_from or wrapper fb = FunctionBuilder.from_func(build_from or 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 for arg, default in expected_items: fb.add_arg(arg, default) # may raise ExistingArgument if fb.is_async: fb.body = 'return await _call(%s)' % fb.get_invocation_str() else: fb.body = 'return _call(%s)' % fb.get_invocation_str() execdict = dict(_call=wrapper, _func=func) fully_wrapped = fb.get_func(execdict, with_dict=update_dict) if hide_wrapped and hasattr(fully_wrapped, '__wrapped__'): del fully_wrapped.__dict__['__wrapped__'] elif not hide_wrapped: fully_wrapped.__wrapped__ = func # ref to the original function (#115) return fully_wrapped def _parse_wraps_expected(expected): # expected takes a pretty powerful argument, it's processed # here. admittedly this would be less trouble if I relied on # OrderedDict (there's an impl of that in the commit history if # you look if expected is None: expected = [] elif isinstance(expected, str): expected = [(expected, NO_DEFAULT)] expected_items = [] try: expected_iter = iter(expected) except TypeError as e: raise ValueError('"expected" takes string name, sequence of string names,' ' iterable of (name, default) pairs, or a mapping of ' ' {name: default}, not %r (got: %r)' % (expected, e)) for argname in expected_iter: if isinstance(argname, str): # dict keys and bare strings try: default = expected[argname] except TypeError: default = NO_DEFAULT else: # pairs try: argname, default = argname except (TypeError, ValueError): raise ValueError('"expected" takes string name, sequence of string names,' ' iterable of (name, default) pairs, or a mapping of ' ' {name: default}, not %r') if not isinstance(argname, str): raise ValueError(f'all "expected" argnames must be strings, not {argname!r}') expected_items.append((argname, default)) return expected_items
[文档] class FunctionBuilder: """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 (tuple): A tuple containing default argument values for those arguments that have defaults. 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: """ _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 {attr: getattr(argspec, attr) for attr in cls._argspec_defaults} _defaults = {'doc': str, 'dict': dict, 'is_async': lambda: False, 'module': lambda: None, 'body': lambda: 'pass', 'indent': lambda: 4, "annotations": dict, '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
[文档] def get_sig_str(self, with_annotations=True): """Return function signature as a string. with_annotations is ignored on Python 2. On Python 3 signature will omit annotations if it is set to False. """ if with_annotations: annotations = self.annotations else: annotations = {} return inspect_formatargspec(self.args, self.varargs, self.varkw, [], self.kwonlyargs, {}, 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 = {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]
[文档] @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(f'expected callable object, not {func!r}') if isinstance(func, functools.partial): kwargs = {'name': func.func.__name__, 'doc': func.func.__doc__, 'module': getattr(func.func, '__module__', None), # e.g., method_descriptor 'annotations': getattr(func.func, "__annotations__", {}), 'dict': getattr(func.func, '__dict__', {})} else: kwargs = {'name': func.__name__, 'doc': func.__doc__, 'module': getattr(func, '__module__', None), # e.g., method_descriptor 'annotations': getattr(func, "__annotations__", {}), 'dict': getattr(func, '__dict__', {})} kwargs.update(cls._argspec_to_dict(func)) if inspect.iscoroutinefunction(func): kwargs['is_async'] = True return cls(**kwargs)
[文档] 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}' if self.is_async: tmpl = 'async ' + tmpl body = _indent(self.body, ' ' * self.indent) name ='<', '_').replace('>', '_') # lambdas src = tmpl.format(name=name, sig_str=self.get_sig_str(with_annotations=False), doc=self.doc, body=body) self._compile(src, execdict) func = execdict[name] func.__name__ = func.__doc__ = self.doc func.__defaults__ = self.defaults func.__kwdefaults__ = self.kwonlydefaults func.__annotations__ = self.annotations if with_dict: func.__dict__.update(self.dict) func.__module__ = self.module # TODO: caller module fallback? if add_source: func.__source__ = src return func
[文档] 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 []))))) kwonlydefaults = getattr(self, 'kwonlydefaults', None) if kwonlydefaults: ret.update(kwonlydefaults) return ret
def get_arg_names(self, only_required=False): arg_names = tuple(self.args) + tuple(getattr(self, 'kwonlyargs', ())) if only_required: defaults_dict = self.get_defaults_dict() arg_names = tuple([an for an in arg_names if an not in defaults_dict]) return arg_names
[文档] def add_arg(self, arg_name, default=NO_DEFAULT, kwonly=False): """Add an argument with optional *default* (defaults to ``funcutils.NO_DEFAULT``). Pass *kwonly=True* to add a keyword-only argument """ if arg_name in self.args: raise ExistingArgument(f'arg {arg_name!r} already in func {} arg list') if arg_name in self.kwonlyargs: raise ExistingArgument(f'arg {arg_name!r} already in func {} kwonly arg list') if not kwonly: self.args.append(arg_name) if default is not NO_DEFAULT: self.defaults = (self.defaults or ()) + (default,) else: self.kwonlyargs.append(arg_name) if default is not NO_DEFAULT: self.kwonlydefaults[arg_name] = default
[文档] 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): # 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 class ExistingArgument(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) from functools import total_ordering def noop(*args, **kwargs): """ Simple function that should be used when no effect is desired. An alternative to checking for an optional function type parameter. e.g. def decorate(func, pre_func=None, post_func=None): if pre_func: pre_func() func() if post_func: post_func() vs def decorate(func, pre_func=noop, post_func=noop): pre_func() func() post_func() """ return None # end