["python","python-2.5","pep8"]
How to properly use python's isinstance() to check if a variable is a number?

I found some old Python code that was doing something like: if type(var) is type(1): ... As expected, pep8 complains about this recommending usage of isinstance(). Now, the problem is that the numbers module was added in Python 2.6 and I need to write code that works with Python 2.5+ So if isinstance(var, Numbers.number) is not a solution. Which would be the proper solution in this case?
In Python 2, you can use the types module: >>> import types >>> var = 1 >>> NumberTypes = (types.IntType, types.LongType, types.FloatType, types.ComplexType) >>> isinstance(var, NumberTypes) True Note the use of a tuple to test against multiple types. Under the hood, IntType is just an alias for int, etc.: >>> isinstance(var, (int, long, float, complex)) True The complex type requires that your python was compiled with support for complex numbers; if you want to guard for this use a try/except block: >>> try: ... NumberTypes = (types.IntType, types.LongType, types.FloatType, types.ComplexType) ... except AttributeError: ... # No support for complex numbers compiled ... NumberTypes = (types.IntType, types.LongType, types.FloatType) ... or if you just use the types directly: >>> try: ... NumberTypes = (int, long, float, complex) ... except NameError: ... # No support for complex numbers compiled ... NumberTypes = (int, long, float) ... In Python 3 types no longer has any standard type aliases, complex is always enabled and there is no longer a long vs int difference, so in Python 3 always use: NumberTypes = (int, float, complex) Last but not least, you can use the numbers.Numbers abstract base type (new in Python 2.6) to also support custom numeric types that don't derive directly from the above types: >>> import numbers >>> isinstance(var, numbers.Number) True This check also returns True for decimal.Decimal() and fractions.Fraction() objects. This module does make the assumption that the complex type is enabled; you'll get an import error if it is not.