Question

In my code, I generate new python classes at runtime. For some of them, I want to generate the python code, just as if I wrote these classes in a .py file.

Let’s say that I created dynamically a class A:
type('A', (), {'bar':True} which is equivalent to the code:

class A(object): 
    bar=True

What I want is to generate this equivalent code from my dynamic class.
I’m trying to implement a function “generate_A_code”

kls_A = type('A', (), {'bar':True}
kls_A.generate_A_code()

Hope this helps a bit.

Thanks

Answer 1

Generating the Python code from the class object itself is practically impossible. You need to save the instructions for generating the class in another way.

---

The best way may be having a function to make the class, and importing & calling it in the generated code. So the generated code would look like this:

kwargs = {answer=42, name='foo'}

import class_maker
SomeClass1 = class_maker.make_class(**kwargs)

---

The other option is generate the Python code you want directly, exec it to make the class, and then save it with the class.

code = '''class MyClass:
    pass
'''

the_locals = {}
exec(code, globals(), the_locals)
MyClass = the_locals['MyClass']
MyClass._code = code

As always with exec, be very careful using it. It can run any Python code. Think hard if there’s any way to do whatever you need to do in a different way. People will shout at you for using exec. (But even the Python standard library uses it for dynamic classes sometimes.)