Determine if a Python class is an Abstract Base Class or Concrete

Question

My Python application contains many abstract classes and implementations. For example:

import abc
import datetime
         


        

Answer 1

You could do this with the _ast module. For example, if your example code were in foo.py you could invoked this function with "foo.py" and "FriendlyMessagePrinter" as arguments.

def is_abstract(filepath, class_name):
    astnode = compile(open(filename).read(), filename, 'exec', _ast.PyCF_ONLY_AST)
    for node in astnode.body:
        if isinstance(node, _ast.ClassDef) and node.name == class_name:
            for funcdef in node.body:
                if isinstance(funcdef, _ast.FunctionDef):
                    if any(not isinstance(n, _ast.Pass) for n in funcdef.body):
                        return False
            return True
    print 'class %s not found in file %s' %(class_name, filepath)