How can I find Python methods without return statements?

Question

I really like when the methods of objects that modify the objects property return self so that you can chain method calls. For instance:

 boundingBox.grow(0.05).shift(x=1.3) 

instead

 boundingBox.grow(0.05) boundingBox.shift(x=1.3) 

I would like to find the code of my old projects to customize this template. How to find methods that do not have a return statement?

Ideally, I want the program to run through a folder. The program looks for Python files, looks for classes, checks their methods, and looks for returned statements. If the return statement does not exist, it returns the file name, class name, and method name.

Answer 1

You can get names using ast, I will work on getting line numbers:

 import inspect import importlib import ast class FindReturn(ast.NodeVisitor): def __init__(self): self.data = [] def visit_ClassDef(self,node): self.data.append(node.name) self.generic_visit(node) def visit_FunctionDef(self, node): if not any(isinstance(n, ast.Return) for n in node.body): self.data.append(node.name) self.generic_visit(node) mod = "test" mod = importlib.import_module(mod) p = ast.parse(inspect.getsource(mod)) f = FindReturn() f.visit(p) print(f.data) 

Input:

 class Foo(object): def __init__(self): self.foo = "foo" def meth1(self): self.bar = "bar" def meth2(self): self.foobar = "foobar" def meth3(self): self.returns = "foobar" return self.returns class Bar(object): def __init__(self): self.foo = "foo" def meth1(self): self.bar = "bar" def meth2(self): self.foobar = "foobar" def meth3(self): self.returns = "foobar" return self.returns 

Output:

 ['Foo', '__init__', 'meth1', 'meth2', 'Bar', '__init__', 'meth1', 'meth2'] 

Here, obviously, the file name is "test.py" .

This is probably a more convenient way to group data:

 import inspect import importlib import ast from collections import defaultdict mod = "test" mod = importlib.import_module(mod) p = ast.parse(inspect.getsource(mod)) data = defaultdict(defaultdict) classes = [cls for cls in p.body if isinstance(cls, ast.ClassDef)] for cls in classes: name = "class_{}".format(cls.name) data[mod][name] = {"methods": []} for node in cls.body: if not any(isinstance(n, ast.Return) for n in node.body): if node.name != "__init__": data[mod][name]["methods"].append(node.name) 

Output:

 {<module 'test' from '/home/padraic/test.pyc'>: defaultdict(None, {'class_Foo': {'methods': ['meth1', 'meth2']}, 'class_Bar': {'methods': ['meth1', 'meth2']}})} 

To go through the directory:

 data = defaultdict(defaultdict) import os path = "/home/padraic/tests" for py in os.listdir(path): with open(os.path.join(path,py)) as f: p = ast.parse(f.read(), "", "exec") classes = [cls for cls in p.body if isinstance(cls, ast.ClassDef)] for cls in classes: name = "class_{}".format(cls.name) data[py][name] = {"methods": []} for node in cls.body: if not any(isinstance(n, ast.Return) for n in node.body): if node.name != "__init__": data[py][name]["methods"].append(node.name) from pprint import pprint as pp pp(dict(data)) {'test.py': defaultdict(None, {'class_Foo': {'methods': ['meth1', 'meth2']}, 'class_Bar': {'methods': ['meth1', 'meth2']}}),'test2.py': defaultdict(None, {'class_Test2': {'methods': ['test1', 'test2']}})} 

Where test2 contains:

 class Test2: def test1(self): pass def test2(self): self.f=4 s = self.test_return() i = 3 def test_return(self): return "Test2" 

You can get the line before the method definition using node.lineno:

 classes = [cls for cls in p.body if isinstance(cls, ast.ClassDef)] for cls in classes: name = "class_{}".format(cls.name) data[py][name] = {"methods": []} for node in cls.body: if not any(isinstance(n, ast.Return) for n in node.body): if node.name != "__init__": data[py][name]["methods"].append({"meth":node.name,"line":node.lineno}) 

Output:

 {'test.py': defaultdict(None, {'class_Foo': {'methods': [{'meth': 'meth1', 'line': 6}, {'meth': 'meth2', 'line': 9}]}, 'class_Bar': {'methods': [{'meth': 'meth1', 'line': 21}, {'meth': 'meth2', 'line': 24}]}}), 'test2.py': defaultdict(None, {'class_Test2': {'methods': [{'meth': 'test1', 'line': 2}, {'meth': 'test2', 'line': 5}]}})} 

Or we can determine where there is no return by getting the line number from the last arg in the body:

 data[py][name]["methods"].append({"meth":node.name,"line": node.body[-1].lineno}) 

Output:

 {'test.py': defaultdict(None, {'class_Foo': {'methods': [{'meth': 'meth1', 'line': 7}, {'meth': 'meth2', 'line': 10}]}, 'class_Bar': {'methods': [{'meth': 'meth1', 'line': 22}, {'meth': 'meth2', 'line': 25}]}}), 'test2.py': defaultdict(None, {'class_Test2': {'methods': [{'meth': 'test1', 'line': 3}, {'meth': 'test2', 'line': 8}]}})} 

It might also be better to use iglob to ignore other files:

 import glob for py in glob.iglob(os.path.join(path,"*.py")): with open(os.path.join(path, py)) as f: p = ast.parse(f.read(), "", "exec")