Determine if Python variable is an instance of a built-in type

Question

I need to determine if a given Python variable is an instance of native type: str, int, float, bool, list, <

Answer 1

You appear to be interested in assuring the simplejson will handle your types. This is done trivially by

try:
    json.dumps( object )
except TypeError:
    print "Can't convert", object

Which is more reliable than trying to guess which types your JSON implementation handles.

Answer 2

For me the best option is:

allowed_modules = set(['numpy'])
def isprimitive(value):
  return not hasattr(value, '__dict__') or \
  value.__class__.__module__ in allowed_modules

This fix when value is a module and value.__class__.__module__ == '__builtin__' will fail.

Answer 3

This is an old question but it seems none of the answers actually answer the specific question: "(How-to) Determine if Python variable is an instance of a built-in type". Note that it's not "[...] of a specific/given built-in type" but of a.

The proper way to determine if a given object is an instance of a buil-in type/class is to check if the type of the object happens to be defined in the module __builtin__.

def is_builtin_class_instance(obj):
    return obj.__class__.__module__ == '__builtin__'

Warning: if obj is a class and not an instance, no matter if that class is built-in or not, True will be returned since a class is also an object, an instance of type (i.e. AnyClass.__class__ is type).