Trace method resolution order at runtime

Question

I am working on some code (not mine) and I try to instand it.

There 16 classes in the inheritance tree.

Here area the class according to inspect.getmro(self.__class__)

• foo_barcheck.views.barcheck.AdminListActionView
• foo_barcheck.views.barcheck.ListActionMixin
• djangotools.utils.urlresolverutils.UrlMixin
• foo.views.ListActionView
• foo.views.ContextMixin
• foo.views.fooMixin
• djangotools.views.ListActionView
• djangotools.views.ListViewMixin
• django.views.generic.list.MultipleObjectMixin
• django.views.generic.edit.FormMixin
• djangotools.views.DTMixin
• django.views.generic.base.TemplateView
• django.views.generic.base.TemplateResponseMixin
• django.views.generic.base.ContextMixin
• django.views.generic.base.View
• object

I want to trace what happens if I call self.do_magic().

I want to see all do_magic() calls of these 16 classes.

The ideal solution would look like this:

result_of_do_magic, list_of_do_magic_methods = trace_method_calls(self.do_magic)

I have no clue how to implement trace_method_calls(). It should execute the code and trace the method calls at runtime.

Is there a tracing guru which knows how to do this?

AFAIK this needs to be done at runtime, since I don't know if all methods calls the do_magic() of the parents via super().

Update

I don't want to modify the code to be able to trace it. I guess this should be possible, since the mocking library can do comparable magic.

Answer 1

If I understand correctly, I can see 2 solutions here.

1) [Brute-ish and relatively easy] Find all occurrences of "do_magic" in your code and wrap it with decorator like:

def trace_this(fn):
    def wrapped(*args, **kwargs):
        print("do_magic is called!")
        result = fn(*args, **kwargs)
        print("Result is:{0}".format(result))
        return result
return wrapped
...
@trace_this
def do_magic():
    ...

2) Run django as:

python -m trace -t manage.py runserver 127.0.0.1:8000 --noreload > trace.txt

and all invoked code would be in trace.txt that you can then parse/analyze with tools you prefer.