Access variables of caller function in Python

What I ended up doing was

scope = locals()

and make scope accessible from do_something. That way I don't have to reach, but I can still access the dictionary of local variables of the caller. This is quite similar to building a dictionary myself and passing it on.

There is no and, in my opinion, should be no elegant way of implementing reach since that introduces a new non-standard indirection which is really hard to comprehend, debug, test and maintain. As the Python mantra (try import this) says:

Explicit is better than implicit.

So, just pass the arguments. You-from-the-future will be really grateful to you-from-today.

Is there a better way to solve this problem? (Other than wrapping the respective data into dicts and pass these dicts explicitly to do_something())

Passing the dicts explicitly is a better way.

What you're proposing sounds very unconventional. When code increases in size, you have to break down the code into a modular architecture, with clean APIs between modules. It also has to be something that is easy to comprehend, easy to explain, and easy to hand over to another programmer to modify/improve/debug it. What you're proposing sounds like it is not a clean API, unconventional, with a non-obvious data flow. I suspect it would probably make many programmers grumpy when they saw it. :)

Another option would be to make the functions members of a class, with the data being in the class instance. That could work well if your problem can be modelled as several functions operating on the data object.