add inspect.getcallargs, which binds function arguments like a normal call #3135
Patch by George Sakkis
This commit is contained in:
Benjamin Peterson
parent
ec71794cb8
commit
7e213255ce
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@ -504,6 +504,32 @@ Classes and functions
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metatype is in use, cls will be the first element of the tuple.
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.. function:: getcallargs(func[, *args][, **kwds])
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Bind the *args* and *kwds* to the argument names of the Python function or
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method *func*, as if it was called with them. For bound methods, bind also the
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first argument (typically named ``self``) to the associated instance. A dict
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is returned, mapping the argument names (including the names of the ``*`` and
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``**`` arguments, if any) to their values from *args* and *kwds*. In case of
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invoking *func* incorrectly, i.e. whenever ``func(*args, **kwds)`` would raise
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an exception because of incompatible signature, an exception of the same type
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and the same or similar message is raised. For example::
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>>> from inspect import getcallargs
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>>> def f(a, b=1, *pos, **named):
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... pass
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>>> getcallargs(f, 1, 2, 3)
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{'a': 1, 'named': {}, 'b': 2, 'pos': (3,)}
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>>> getcallargs(f, a=2, x=4)
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{'a': 2, 'named': {'x': 4}, 'b': 1, 'pos': ()}
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>>> getcallargs(f)
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Traceback (most recent call last):
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...
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TypeError: f() takes at least 1 argument (0 given)
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.. versionadded:: 2.7
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.. _inspect-stack:
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The interpreter stack
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@ -17,7 +17,7 @@ Here are some of the useful functions provided by this module:
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getmodule() - determine the module that an object came from
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getclasstree() - arrange classes so as to represent their hierarchy
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getargspec(), getargvalues() - get info about function arguments
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getargspec(), getargvalues(), getcallargs() - get info about function arguments
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formatargspec(), formatargvalues() - format an argument spec
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getouterframes(), getinnerframes() - get info about frames
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currentframe() - get the current stack frame
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@ -884,6 +884,89 @@ def formatargvalues(args, varargs, varkw, locals,
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specs.append(formatvarkw(varkw) + formatvalue(locals[varkw]))
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return '(' + string.join(specs, ', ') + ')'
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def getcallargs(func, *positional, **named):
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"""Get the mapping of arguments to values.
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A dict is returned, with keys the function argument names (including the
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names of the * and ** arguments, if any), and values the respective bound
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values from 'positional' and 'named'."""
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args, varargs, varkw, defaults = getargspec(func)
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f_name = func.__name__
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arg2value = {}
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# The following closures are basically because of tuple parameter unpacking.
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assigned_tuple_params = []
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def assign(arg, value):
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if isinstance(arg, str):
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arg2value[arg] = value
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else:
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assigned_tuple_params.append(arg)
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value = iter(value)
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for i, subarg in enumerate(arg):
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try:
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subvalue = next(value)
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except StopIteration:
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raise ValueError('need more than %d %s to unpack' %
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(i, 'values' if i > 1 else 'value'))
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assign(subarg,subvalue)
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try:
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next(value)
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except StopIteration:
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pass
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else:
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raise ValueError('too many values to unpack')
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def is_assigned(arg):
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if isinstance(arg,str):
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return arg in arg2value
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return arg in assigned_tuple_params
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if ismethod(func) and func.im_self is not None:
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# implicit 'self' (or 'cls' for classmethods) argument
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positional = (func.im_self,) + positional
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num_pos = len(positional)
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num_total = num_pos + len(named)
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num_args = len(args)
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num_defaults = len(defaults) if defaults else 0
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for arg, value in zip(args, positional):
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assign(arg, value)
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if varargs:
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if num_pos > num_args:
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assign(varargs, positional[-(num_pos-num_args):])
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else:
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assign(varargs, ())
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elif 0 < num_args < num_pos:
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raise TypeError('%s() takes %s %d %s (%d given)' % (
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f_name, 'at most' if defaults else 'exactly', num_args,
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'arguments' if num_args > 1 else 'argument', num_total))
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elif num_args == 0 and num_total:
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raise TypeError('%s() takes no arguments (%d given)' %
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(f_name, num_total))
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for arg in args:
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if isinstance(arg, str) and arg in named:
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if is_assigned(arg):
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raise TypeError("%s() got multiple values for keyword "
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"argument '%s'" % (f_name, arg))
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else:
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assign(arg, named.pop(arg))
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if defaults: # fill in any missing values with the defaults
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for arg, value in zip(args[-num_defaults:], defaults):
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if not is_assigned(arg):
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assign(arg, value)
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if varkw:
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assign(varkw, named)
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elif named:
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unexpected = next(iter(named))
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if isinstance(unexpected, unicode):
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unexpected = unexpected.encode(sys.getdefaultencoding(), 'replace')
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raise TypeError("%s() got an unexpected keyword argument '%s'" %
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(f_name, unexpected))
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unassigned = num_args - len([arg for arg in args if is_assigned(arg)])
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if unassigned:
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num_required = num_args - num_defaults
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raise TypeError('%s() takes %s %d %s (%d given)' % (
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f_name, 'at least' if defaults else 'exactly', num_required,
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'arguments' if num_required > 1 else 'argument', num_total))
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return arg2value
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# -------------------------------------------------- stack frame extraction
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Traceback = namedtuple('Traceback', 'filename lineno function code_context index')
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@ -1,8 +1,11 @@
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import re
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import sys
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import types
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import unittest
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import inspect
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import datetime
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from UserList import UserList
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from UserDict import UserDict
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from test.test_support import run_unittest, check_py3k_warnings
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@ -557,10 +560,197 @@ class TestClassesAndFunctions(unittest.TestCase):
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self.assertIn(('m1', 'method', D), attrs, 'missing plain method')
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self.assertIn(('datablob', 'data', A), attrs, 'missing data')
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class TestGetcallargsFunctions(unittest.TestCase):
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# tuple parameters are named '.1', '.2', etc.
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is_tuplename = re.compile(r'^\.\d+$').match
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def assertEqualCallArgs(self, func, call_params_string, locs=None):
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locs = dict(locs or {}, func=func)
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r1 = eval('func(%s)' % call_params_string, None, locs)
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r2 = eval('inspect.getcallargs(func, %s)' % call_params_string, None,
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locs)
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self.assertEqual(r1, r2)
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def assertEqualException(self, func, call_param_string, locs=None):
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locs = dict(locs or {}, func=func)
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try:
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eval('func(%s)' % call_param_string, None, locs)
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except Exception, ex1:
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pass
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else:
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self.fail('Exception not raised')
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try:
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eval('inspect.getcallargs(func, %s)' % call_param_string, None,
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locs)
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except Exception, ex2:
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pass
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else:
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self.fail('Exception not raised')
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self.assertIs(type(ex1), type(ex2))
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self.assertEqual(str(ex1), str(ex2))
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def makeCallable(self, signature):
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"""Create a function that returns its locals(), excluding the
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autogenerated '.1', '.2', etc. tuple param names (if any)."""
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code = ("lambda %s: dict(i for i in locals().items() "
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"if not is_tuplename(i[0]))")
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return eval(code % signature, {'is_tuplename' : self.is_tuplename})
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def test_plain(self):
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f = self.makeCallable('a, b=1')
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self.assertEqualCallArgs(f, '2')
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self.assertEqualCallArgs(f, '2, 3')
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self.assertEqualCallArgs(f, 'a=2')
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self.assertEqualCallArgs(f, 'b=3, a=2')
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self.assertEqualCallArgs(f, '2, b=3')
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# expand *iterable / **mapping
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self.assertEqualCallArgs(f, '*(2,)')
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self.assertEqualCallArgs(f, '*[2]')
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self.assertEqualCallArgs(f, '*(2, 3)')
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self.assertEqualCallArgs(f, '*[2, 3]')
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self.assertEqualCallArgs(f, '**{"a":2}')
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self.assertEqualCallArgs(f, 'b=3, **{"a":2}')
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self.assertEqualCallArgs(f, '2, **{"b":3}')
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self.assertEqualCallArgs(f, '**{"b":3, "a":2}')
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# expand UserList / UserDict
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self.assertEqualCallArgs(f, '*UserList([2])')
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self.assertEqualCallArgs(f, '*UserList([2, 3])')
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self.assertEqualCallArgs(f, '**UserDict(a=2)')
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self.assertEqualCallArgs(f, '2, **UserDict(b=3)')
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self.assertEqualCallArgs(f, 'b=2, **UserDict(a=3)')
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# unicode keyword args
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self.assertEqualCallArgs(f, '**{u"a":2}')
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self.assertEqualCallArgs(f, 'b=3, **{u"a":2}')
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self.assertEqualCallArgs(f, '2, **{u"b":3}')
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self.assertEqualCallArgs(f, '**{u"b":3, u"a":2}')
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def test_varargs(self):
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f = self.makeCallable('a, b=1, *c')
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self.assertEqualCallArgs(f, '2')
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self.assertEqualCallArgs(f, '2, 3')
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self.assertEqualCallArgs(f, '2, 3, 4')
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self.assertEqualCallArgs(f, '*(2,3,4)')
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self.assertEqualCallArgs(f, '2, *[3,4]')
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self.assertEqualCallArgs(f, '2, 3, *UserList([4])')
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def test_varkw(self):
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f = self.makeCallable('a, b=1, **c')
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self.assertEqualCallArgs(f, 'a=2')
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self.assertEqualCallArgs(f, '2, b=3, c=4')
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self.assertEqualCallArgs(f, 'b=3, a=2, c=4')
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self.assertEqualCallArgs(f, 'c=4, **{"a":2, "b":3}')
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self.assertEqualCallArgs(f, '2, c=4, **{"b":3}')
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self.assertEqualCallArgs(f, 'b=2, **{"a":3, "c":4}')
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self.assertEqualCallArgs(f, '**UserDict(a=2, b=3, c=4)')
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self.assertEqualCallArgs(f, '2, c=4, **UserDict(b=3)')
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self.assertEqualCallArgs(f, 'b=2, **UserDict(a=3, c=4)')
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# unicode keyword args
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self.assertEqualCallArgs(f, 'c=4, **{u"a":2, u"b":3}')
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self.assertEqualCallArgs(f, '2, c=4, **{u"b":3}')
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self.assertEqualCallArgs(f, 'b=2, **{u"a":3, u"c":4}')
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def test_tupleargs(self):
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f = self.makeCallable('(b,c), (d,(e,f))=(0,[1,2])')
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self.assertEqualCallArgs(f, '(2,3)')
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self.assertEqualCallArgs(f, '[2,3]')
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self.assertEqualCallArgs(f, 'UserList([2,3])')
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self.assertEqualCallArgs(f, '(2,3), (4,(5,6))')
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self.assertEqualCallArgs(f, '(2,3), (4,[5,6])')
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self.assertEqualCallArgs(f, '(2,3), [4,UserList([5,6])]')
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def test_multiple_features(self):
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f = self.makeCallable('a, b=2, (c,(d,e))=(3,[4,5]), *f, **g')
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self.assertEqualCallArgs(f, '2, 3, (4,[5,6]), 7')
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self.assertEqualCallArgs(f, '2, 3, *[(4,[5,6]), 7], x=8')
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self.assertEqualCallArgs(f, '2, 3, x=8, *[(4,[5,6]), 7]')
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self.assertEqualCallArgs(f, '2, x=8, *[3, (4,[5,6]), 7], y=9')
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self.assertEqualCallArgs(f, 'x=8, *[2, 3, (4,[5,6])], y=9')
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self.assertEqualCallArgs(f, 'x=8, *UserList([2, 3, (4,[5,6])]), '
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'**{"y":9, "z":10}')
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self.assertEqualCallArgs(f, '2, x=8, *UserList([3, (4,[5,6])]), '
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'**UserDict(y=9, z=10)')
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def test_errors(self):
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f0 = self.makeCallable('')
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f1 = self.makeCallable('a, b')
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f2 = self.makeCallable('a, b=1')
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# f0 takes no arguments
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self.assertEqualException(f0, '1')
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self.assertEqualException(f0, 'x=1')
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self.assertEqualException(f0, '1,x=1')
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# f1 takes exactly 2 arguments
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self.assertEqualException(f1, '')
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self.assertEqualException(f1, '1')
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self.assertEqualException(f1, 'a=2')
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self.assertEqualException(f1, 'b=3')
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# f2 takes at least 1 argument
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self.assertEqualException(f2, '')
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self.assertEqualException(f2, 'b=3')
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for f in f1, f2:
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# f1/f2 takes exactly/at most 2 arguments
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self.assertEqualException(f, '2, 3, 4')
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self.assertEqualException(f, '1, 2, 3, a=1')
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self.assertEqualException(f, '2, 3, 4, c=5')
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self.assertEqualException(f, '2, 3, 4, a=1, c=5')
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# f got an unexpected keyword argument
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self.assertEqualException(f, 'c=2')
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self.assertEqualException(f, '2, c=3')
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self.assertEqualException(f, '2, 3, c=4')
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self.assertEqualException(f, '2, c=4, b=3')
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self.assertEqualException(f, '**{u"\u03c0\u03b9": 4}')
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# f got multiple values for keyword argument
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self.assertEqualException(f, '1, a=2')
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self.assertEqualException(f, '1, **{"a":2}')
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self.assertEqualException(f, '1, 2, b=3')
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# XXX: Python inconsistency
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# - for functions and bound methods: unexpected keyword 'c'
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# - for unbound methods: multiple values for keyword 'a'
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#self.assertEqualException(f, '1, c=3, a=2')
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f = self.makeCallable('(a,b)=(0,1)')
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self.assertEqualException(f, '1')
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self.assertEqualException(f, '[1]')
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self.assertEqualException(f, '(1,2,3)')
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class TestGetcallargsMethods(TestGetcallargsFunctions):
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def setUp(self):
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class Foo(object):
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pass
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self.cls = Foo
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self.inst = Foo()
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def makeCallable(self, signature):
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assert 'self' not in signature
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mk = super(TestGetcallargsMethods, self).makeCallable
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self.cls.method = mk('self, ' + signature)
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return self.inst.method
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class TestGetcallargsUnboundMethods(TestGetcallargsMethods):
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def makeCallable(self, signature):
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super(TestGetcallargsUnboundMethods, self).makeCallable(signature)
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return self.cls.method
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def assertEqualCallArgs(self, func, call_params_string, locs=None):
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return super(TestGetcallargsUnboundMethods, self).assertEqualCallArgs(
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*self._getAssertEqualParams(func, call_params_string, locs))
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def assertEqualException(self, func, call_params_string, locs=None):
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return super(TestGetcallargsUnboundMethods, self).assertEqualException(
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*self._getAssertEqualParams(func, call_params_string, locs))
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def _getAssertEqualParams(self, func, call_params_string, locs=None):
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assert 'inst' not in call_params_string
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locs = dict(locs or {}, inst=self.inst)
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return (func, 'inst,' + call_params_string, locs)
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def test_main():
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run_unittest(TestDecorators, TestRetrievingSourceCode, TestOneliners,
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TestBuggyCases,
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TestInterpreterStack, TestClassesAndFunctions, TestPredicates)
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run_unittest(
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TestDecorators, TestRetrievingSourceCode, TestOneliners, TestBuggyCases,
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TestInterpreterStack, TestClassesAndFunctions, TestPredicates,
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TestGetcallargsFunctions, TestGetcallargsMethods,
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TestGetcallargsUnboundMethods)
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if __name__ == "__main__":
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test_main()
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@ -32,6 +32,9 @@ Core and Builtins
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Library
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-------
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- Issue #3135: Add inspect.getcallargs, which binds arguments to a function like
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a normal call.
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- Backwards incompatible change: Unicode codepoints line tabulation (0x0B) and
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form feed (0x0C) are now considered linebreaks, as specified in Unicode
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Standard Annex #14. See issue #7643.
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