Importing a python module without actually executing it

Question

In the context of a complex application, I need to import user-supplied 'scripts'. Ideally, a script would have def init(): blah def execute(): more blah def cleanup(): yadda so I'd just import imp fname, path, desc = imp.find_module(userscript) foo = imp.load_module(userscript, fname, path, desc) foo.init() However, as we all know, the user's script is executed as soon as load_module runs. Which means, a script can be something like this: def init(): blah yadda yielding to the yadda part being called as soon as I import the script. What I need is a way to: check first whether it has init(), execute() and cleanup() if they exist, all is well if they don't exist, complain don't run any other code, or at least not until I know there's no init() Normally I'd force the use the same old if __name__ == '__main__' trick, but I have little control on the user-supplied script, so I'm looking for a relatively painless solution. I have seen all sorts of complicated tricks, including parsing the script, but nothing really simple. I'm surprised it does not exist.. or maybe I'm not getting something. Thanks. JavaScript questions and answers, JavaScript questions pdf, JavaScript question bank, JavaScript questions and answers pdf, mcq on JavaScript pdf, JavaScript questions and solutions, JavaScript mcq Test , Interview JavaScript questions, JavaScript Questions for Interview, JavaScript MCQ (Multiple Choice Questions)

Answer 1

My attempt using the ast module: import ast # which syntax elements are allowed at module level? whitelist = [ # docstring lambda x: isinstance(x, ast.Expr) \ and isinstance(x.value, ast.Str), # import lambda x: isinstance(x, ast.Import), # class lambda x: isinstance(x, ast.ClassDef), # function lambda x: isinstance(x, ast.FunctionDef), ] def validate(source, required_functions): tree = ast.parse(source) functions = set() required_functions = set(required_functions) for item in tree.body: if isinstance(item, ast.FunctionDef): functions.add(item.name) continue if all(not checker(item) for checker in whitelist): return False # at least the required functions must be there return len(required_functions - functions) == 0 if __name__ == "__main__": required_funcs = [ "init", "execute", "cleanup" ] with open("/tmp/test.py", "rb") as f: print("yay!" if validate(f.read(), required_funcs) else "d'oh!")