Source code for pytyp.spec.check

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# The Original Code is Pytyp (http://www.acooke.org/pytyp)
# The Initial Developer of the Original Code is Andrew Cooke.
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from inspect import getcallargs, getfullargspec
from functools import wraps

from pytyp.spec.abcs import type_error, normalize


[docs]def verify(value, spec): ''' If ``value`` is *not* an instance of ``spec`` then raise a ``TypeError``. ''' spec = normalize(spec) if not isinstance(value, spec): type_error(value, spec)
def verify_all(callargs, annotations): ''' Helper to verify a set of values against the appropriate type annotations.sy ''' for name in annotations: spec = annotations[name] try: verify(callargs.get(name), spec) except AttributeError: pass def unpack(func): ''' Separate the return specification from the rest. ''' annotations = dict((name, normalize(spec)) for (name, spec) in getfullargspec(func).annotations.items()) try: rspec = annotations.pop('return') do_return = True except KeyError: rspec = None do_return = False return (annotations, do_return, rspec)
[docs]def checked(func): ''' A decorator that adds runtime verification of type annotations to a function or method. >>> @checked ... def str_len(s:str) -> int: ... return len(s) >>> str_len('abc') 3 >>> str_len([1,2,3]) Traceback (most recent call last): ... TypeError: Type str inconsistent with [1, 2, 3]. >>> @checked ... def bad_len(s:str) -> int: ... return 'wrong' >>> bad_len('abc') Traceback (most recent call last): ... TypeError: Type int inconsistent with 'wrong'. ''' (annotations, do_return, rspec) = unpack(func) @wraps(func) def wrapper(*args, **kargs): callargs = getcallargs(func, *args, **kargs) verify_all(callargs, annotations) result = func(*args, **kargs) if do_return: verify(result, rspec) return result return wrapper
if __name__ == "__main__": import doctest print(doctest.testmod())