Pyreverse: how to add return types for methods and properties when generating uml reports?

I am successfully generating UML reports from Python modules using pyreverse and graphviz. I can see that pylint is smart enough to say for some properties what is the output data type, but not for all and none for the methods.

The source code:

def get_int():
    return 555

def get_math_int():
    return math.pow(2, 5)

class ClassFoo(object):
    def __init__(self, x, y):
        self.attr1 = "hello"
        self.attr2 = get_int()
        self.attr3 = get_math_int()

    def spam(self):
        return 77

class ClassBar(object):
    def __init__(self, x, y):
        self.attr4 = "hello"

    def spam(self):
        return 99

The output pdf

I have looked into pylint docstyle checker but it looked irrelevant for my problem.

Is it possible to explicitly specify using either a type hint through comment, docstring or somehow else what data type will be returned by each method and attribute so that they will be shown in the pdf report?

In Python 3.5 or later, you could use the built-in typings module; in Python 2 or older versions of Python 3, mypy is your only option. A good IDE (PyCharm, for example), will actually tell you if you're making errors if all of your classes are well-annotated.

Extracting type information is pretty painful, but starts with reading the __annotations__ attribute on classes that have type hints (see PEP-0484).

Your example, fully type-hinted using Python 3.5 or later:

from typing import Any

def get_int() -> int:
    return 555

def get_math_int() -> int:
    return math.pow(2, 5)

class ClassFoo(object):
    def __init__(self, x: Any, y: Any):
        self.attr1 = "hello"
        self.attr2 = get_int()
        self.attr3 = get_math_int()

    def spam(self) -> int:
        return 77

class ClassBar(object):
    def __init__(self, x: Any, y: Any):
        self.attr4 = "hello"

    def spam(self) -> int:
        return 99