greatly improve argument parsing error messages (closes #12265)
diff --git a/Lib/inspect.py b/Lib/inspect.py
index 4899cbf..f200a82 100644
--- a/Lib/inspect.py
+++ b/Lib/inspect.py
@@ -914,6 +914,29 @@
specs.append(formatvarkw(varkw) + formatvalue(locals[varkw]))
return '(' + ', '.join(specs) + ')'
+def _positional_error(f_name, args, kwonly, varargs, defcount, given, values):
+ atleast = len(args) - defcount
+ if given is None:
+ given = len([arg for arg in args if arg in values])
+ kwonly_given = len([arg for arg in kwonly if arg in values])
+ if varargs:
+ plural = atleast != 1
+ sig = "at least %d" % (atleast,)
+ elif defcount:
+ plural = True
+ sig = "from %d to %d" % (atleast, len(args))
+ else:
+ plural = len(args) != 1
+ sig = str(len(args))
+ kwonly_sig = ""
+ if kwonly_given:
+ msg = " positional argument%s (and %d keyword-only argument%s)"
+ kwonly_sig = (msg % ("s" if given != 1 else "", kwonly_given,
+ "s" if kwonly_given != 1 else ""))
+ raise TypeError("%s() takes %s positional argument%s but %d%s %s given" %
+ (f_name, sig, "s" if plural else "", given, kwonly_sig,
+ "was" if given == 1 and not kwonly_given else "were"))
+
def getcallargs(func, *positional, **named):
"""Get the mapping of arguments to values.
@@ -925,64 +948,50 @@
f_name = func.__name__
arg2value = {}
+
if ismethod(func) and func.__self__ is not None:
# implicit 'self' (or 'cls' for classmethods) argument
positional = (func.__self__,) + positional
num_pos = len(positional)
- num_total = num_pos + len(named)
num_args = len(args)
num_defaults = len(defaults) if defaults else 0
- for arg, value in zip(args, positional):
- arg2value[arg] = value
- if varargs:
- if num_pos > num_args:
- arg2value[varargs] = positional[-(num_pos-num_args):]
- else:
- arg2value[varargs] = ()
- elif 0 < num_args < num_pos:
- raise TypeError('%s() takes %s %d positional %s (%d given)' % (
- f_name, 'at most' if defaults else 'exactly', num_args,
- 'arguments' if num_args > 1 else 'argument', num_total))
- elif num_args == 0 and num_total:
- if varkw or kwonlyargs:
- if num_pos:
- # XXX: We should use num_pos, but Python also uses num_total:
- raise TypeError('%s() takes exactly 0 positional arguments '
- '(%d given)' % (f_name, num_total))
- else:
- raise TypeError('%s() takes no arguments (%d given)' %
- (f_name, num_total))
- for arg in itertools.chain(args, kwonlyargs):
- if arg in named:
- if arg in arg2value:
- raise TypeError("%s() got multiple values for keyword "
- "argument '%s'" % (f_name, arg))
- else:
- arg2value[arg] = named.pop(arg)
- for kwonlyarg in kwonlyargs:
- if kwonlyarg not in arg2value:
- try:
- arg2value[kwonlyarg] = kwonlydefaults[kwonlyarg]
- except KeyError:
- raise TypeError("%s() needs keyword-only argument %s" %
- (f_name, kwonlyarg))
- if defaults: # fill in any missing values with the defaults
- for arg, value in zip(args[-num_defaults:], defaults):
- if arg not in arg2value:
- arg2value[arg] = value
+ n = min(num_pos, num_args)
+ for i in range(n):
+ arg2value[args[i]] = positional[i]
+ if varargs:
+ arg2value[varargs] = tuple(positional[n:])
+ possible_kwargs = set(args + kwonlyargs)
if varkw:
- arg2value[varkw] = named
- elif named:
- unexpected = next(iter(named))
- raise TypeError("%s() got an unexpected keyword argument '%s'" %
- (f_name, unexpected))
- unassigned = num_args - len([arg for arg in args if arg in arg2value])
- if unassigned:
- num_required = num_args - num_defaults
- raise TypeError('%s() takes %s %d %s (%d given)' % (
- f_name, 'at least' if defaults else 'exactly', num_required,
- 'arguments' if num_required > 1 else 'argument', num_total))
+ arg2value[varkw] = {}
+ for kw, value in named.items():
+ if kw not in possible_kwargs:
+ if not varkw:
+ raise TypeError("%s() got an unexpected keyword argument %r" %
+ (f_name, kw))
+ arg2value[varkw][kw] = value
+ continue
+ if kw in arg2value:
+ raise TypeError("%s() got multiple values for argument %r" %
+ (f_name, kw))
+ arg2value[kw] = value
+ if num_pos > num_args and not varargs:
+ _positional_error(f_name, args, kwonlyargs, varargs, num_defaults,
+ num_pos, arg2value)
+ if num_pos < num_args:
+ for arg in args[:num_args - num_defaults]:
+ if arg not in arg2value:
+ _positional_error(f_name, args, kwonlyargs, varargs,
+ num_defaults, None, arg2value)
+ for i, arg in enumerate(args[num_args - num_defaults:]):
+ if arg not in arg2value:
+ arg2value[arg] = defaults[i]
+ for kwarg in kwonlyargs:
+ if kwarg not in arg2value:
+ if kwarg not in kwonlydefaults:
+ raise TypeError("%s() requires keyword-only argument %r" %
+ (f_name, kwarg))
+ arg2value[kwarg] = kwonlydefaults[kwarg]
return arg2value
# -------------------------------------------------- stack frame extraction
diff --git a/Lib/test/test_extcall.py b/Lib/test/test_extcall.py
index 1f7f630..49d5441 100644
--- a/Lib/test/test_extcall.py
+++ b/Lib/test/test_extcall.py
@@ -66,17 +66,17 @@
>>> g()
Traceback (most recent call last):
...
- TypeError: g() takes at least 1 argument (0 given)
+ TypeError: g() takes at least 1 positional argument but 0 were given
>>> g(*())
Traceback (most recent call last):
...
- TypeError: g() takes at least 1 argument (0 given)
+ TypeError: g() takes at least 1 positional argument but 0 were given
>>> g(*(), **{})
Traceback (most recent call last):
...
- TypeError: g() takes at least 1 argument (0 given)
+ TypeError: g() takes at least 1 positional argument but 0 were given
>>> g(1)
1 () {}
@@ -151,7 +151,7 @@
>>> g(1, 2, 3, **{'x': 4, 'y': 5})
Traceback (most recent call last):
...
- TypeError: g() got multiple values for keyword argument 'x'
+ TypeError: g() got multiple values for argument 'x'
>>> f(**{1:2})
Traceback (most recent call last):
@@ -263,29 +263,91 @@
>>> f(**x)
1 2
-A obscure message:
+Some additional tests about positional argument errors:
>>> def f(a, b):
... pass
>>> f(b=1)
Traceback (most recent call last):
...
- TypeError: f() takes exactly 2 arguments (1 given)
-
-The number of arguments passed in includes keywords:
+ TypeError: f() takes 2 positional arguments but 1 was given
>>> def f(a):
... pass
>>> f(6, a=4, *(1, 2, 3))
Traceback (most recent call last):
...
- TypeError: f() takes exactly 1 positional argument (5 given)
+ TypeError: f() got multiple values for argument 'a'
>>> def f(a, *, kw):
... pass
>>> f(6, 4, kw=4)
Traceback (most recent call last):
...
- TypeError: f() takes exactly 1 positional argument (3 given)
+ TypeError: f() takes 1 positional argument but 2 positional arguments (and 1 keyword-only argument) were given
+
+ >>> def f(a):
+ ... pass
+ >>> f()
+ Traceback (most recent call last):
+ ...
+ TypeError: f() takes 1 positional argument but 0 were given
+
+ >>> def f(a, b):
+ ... pass
+ >>> f(1)
+ Traceback (most recent call last):
+ ...
+ TypeError: f() takes 2 positional arguments but 1 was given
+
+ >>> def f(a, *b):
+ ... pass
+ >>> f()
+ Traceback (most recent call last):
+ ...
+ TypeError: f() takes at least 1 positional argument but 0 were given
+
+ >>> def f(a, *, kw=4):
+ ... pass
+ >>> f(kw=4)
+ Traceback (most recent call last):
+ ...
+ TypeError: f() takes 1 positional argument but 0 positional arguments (and 1 keyword-only argument) were given
+
+ >>> def f(a, b=2):
+ ... pass
+ >>> f()
+ Traceback (most recent call last):
+ ...
+ TypeError: f() takes from 1 to 2 positional arguments but 0 were given
+
+ >>> def f(a, *b):
+ ... pass
+ >>> f()
+ Traceback (most recent call last):
+ ...
+ TypeError: f() takes at least 1 positional argument but 0 were given
+
+ >>> def f(*, kw):
+ ... pass
+ >>> f(3, kw=4)
+ Traceback (most recent call last):
+ ...
+ TypeError: f() takes 0 positional arguments but 1 positional argument (and 1 keyword-only argument) were given
+
+ >>> def f(a, c=3, *b, kw):
+ ... pass
+ >>> f()
+ Traceback (most recent call last):
+ ...
+ TypeError: f() takes at least 1 positional argument but 0 were given
+ >>> f(kw=3)
+ Traceback (most recent call last):
+ ...
+ TypeError: f() takes at least 1 positional argument but 0 positional arguments (and 1 keyword-only argument) were given
+ >>> f(kw=3, c=4)
+ Traceback (most recent call last):
+ ...
+ TypeError: f() takes at least 1 positional argument but 1 positional argument (and 1 keyword-only argument) were given
"""
import sys
diff --git a/Lib/test/test_keywordonlyarg.py b/Lib/test/test_keywordonlyarg.py
index d7f7541..44be32c 100644
--- a/Lib/test/test_keywordonlyarg.py
+++ b/Lib/test/test_keywordonlyarg.py
@@ -78,7 +78,7 @@
pass
with self.assertRaises(TypeError) as exc:
f(1, 2, 3)
- expected = "f() takes at most 2 positional arguments (3 given)"
+ expected = "f() takes from 1 to 2 positional arguments but 3 were given"
self.assertEqual(str(exc.exception), expected)
def testSyntaxErrorForFunctionCall(self):