def expect_kinds(**named):
"""
Preprocessing decorator that verifies inputs have expected dtype kinds.
Examples
--------
>>> from numpy import int64, int32, float32
>>> @expect_kinds(x='i')
... def foo(x):
... return x
...
>>> foo(int64(2))
2
>>> foo(int32(2))
2
>>> foo(float32(2)) # doctest: +NORMALIZE_WHITESPACE +ELLIPSIS
Traceback (most recent call last):
...
TypeError: ...foo() expected a numpy object of kind 'i' for argument 'x',
but got 'f' instead.
"""
for name, kind in iteritems(named):
if not isinstance(kind, (str, tuple)):
raise TypeError(
"expect_dtype_kinds() expected a string or tuple of strings"
" for argument {name!r}, but got {kind} instead.".format(
name=name, kind=dtype,
)
)
@preprocess(kinds=call(lambda x: x if isinstance(x, tuple) else (x,)))
def _expect_kind(kinds):
"""
Factory for kind-checking functions that work the @preprocess
decorator.
"""
def error_message(func, argname, value):
# If the bad value has a dtype, but it's wrong, show the dtype
# kind. Otherwise just show the value.
try:
value_to_show = value.dtype.kind
except AttributeError:
value_to_show = value
return (
"{funcname}() expected a numpy object of kind {kinds} "
"for argument {argname!r}, but got {value!r} instead."
).format(
funcname=_qualified_name(func),
kinds=' or '.join(map(repr, kinds)),
argname=argname,
value=value_to_show,
)
def _actual_preprocessor(func, argname, argvalue):
if getattrs(argvalue, ('dtype', 'kind'), object()) not in kinds:
raise TypeError(error_message(func, argname, argvalue))
return argvalue
return _actual_preprocessor
return preprocess(**valmap(_expect_kind, named))
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