Python runtime type checking concept

type_checking.py

# Runtime type checking concept

from functools import wraps

def signature(*types):
  def decorator(func):
    @wraps(func)
    def wrapper(*args, **kwargs):
      for i, t in enumerate(types):
        if i >= len(args):
          raise TypeError("%s typed arguments expected (%s given)" % (len(types), len(args)))
        if not isinstance(args[i], t):
          raise TypeError("%s() arg %s expected to be %r (%r given)" % (func.__name__, i + 1, type(args[i]), t))
      return func(*args, **kwargs)  
    return wrapper
  return decorator

 
@signature(int, int)
def foo(a, b):
  print a + b

foo(2, 3)
foo(2, '3')