how to read python code better? [closed]

Question

without explicit (type) declaration I struggle to try to figure out how things work --- are there some good thumbs of rule/tips that you may have for reading python code better? Thanks!

Answer 1

In spite of the first impression that this question gives, I think it is indeed really intelligent because it reveals that you are subconscious of something that should interest any Python's developper but that I find very neglected in general and in explanations in particular, if not misunderstood.

I mean that IMO the base of Python is terrificly quaint and intelligent: it's the data model on which it has been conceived.
In this Python's data model, there are no variables in the sense of "chunks of memory whose contents can change", contrary to other languages, and in the sense that we don't manage this precise kind of variables in Python.

More precisely, all is object in Python, and every object is named and designed with an identifier, but neither the object nor the identifier are 'variables' in the said sense.

That doesn't mean that there are no little boxes, so called variables in other languages, temporarily hosting values that go in and out of them, in the depthes of the implementation.

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Say an object is designed with the identifier XYA2.
Personally I use this appearance of letters to designate any identifier. An identifier is nothing else than a word written in a code. It is what appears in a code.
Note that this appearance of letters is the one used by this stackoverflow.com site to represent a code sample inside text, by clicking on the button {}. That's easy to remind.

Now, the object whose name is XYA2 is a real thing, a concrete set of bits lying in the memory of the computer to represent the desired conceptual value that it stands for.
This set is defined in C language in which Python is implemented.
Personnaly, I bold the letters when I want to designate an object.
Then the object of name XYA2 is, for me, refered to by XYA2

The identifier is XYA2
It is linked to an underlying and inaccessible pointer that points to the object.
This link is done by means of the symbol table. You will see very few references or allusions to symbol table in general, here on stackoverflow or elsewhere. However it's very important, I think.

The pointer linked to the identifier XYA2 points to the object XYA2
So, XYA2 is directly linked to the pointer and indirectly linked to the object.
Instead of saying "indirectly linked", we say "assigned". An object and its identifier are reciprocally assigned one to the other, but the medium of this link is the underlying pointer.

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And now, something important.
Strictly speaking, a variable is a "chunk of memory whose content can change".
I personally do efforts to never use the word 'variable' in an other sense that this one.
The problem is that, because of the use of the word 'variable' in mathematics, this word is very often used indiscriminately and thrown in all the wind's directions by many developpers (not all) even when it isn't justified.
Thereby, it is commonly used by nearly everybody to designates the names, aka the identifiers in a code. But this practice is horribly confusing. It should be carefully avoided.

That said, an object in Python is not only an instance of some class, it is above all a concrete set of bits; set which IS NOT, as far as I know, a variable, in the sense of "chunk of memory whose content can change".
Hence my opinion that there aren't variables in Python, since the only entities we can access to and manipulate are identifiers and objects.

However, the processes under the hood in an executed Python program use quantities of pointers that are, as far as I know, real variables in the strict sense of this word.
So, in a sense, it could be said that my affirmation 'There are no variables in Python" is false.
It's a matter of point of view.
As a developer in Python, conceptually speaking, I don't manage variables. When I think to an algorithm, I don't think at the level of the pointers, even if I know they exist and that it's very important to know they exist. Being not at the level of the variables, but at the level of the Python's data model, I don't see why I should accept to believe that there are variables in a Python program. There are variables at the machine low-level, and Python is a very-high-level language.

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Why did I write all this ?

1)
because the nature of the Python's data model has quantities of consequences that can't be understood if this data model isn't known. Among these consequences, some are interesting because they give incredible possibilities, others are traps (a well known example is: modifying an element in a copied list modifies also the element in the original list). That's why it's of first importance to learn about this data model.

For that, I recommend you to read these parts of the documentation:
3.1 of objects-values-and-types
4.1 of naming-and-binding

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2)
To justify my answer to your perplexity: don't struggle about what happens under the hood:
there's a garbage colector, a reference counter, wagons of underlying dictionaries-like entities, a thunderous ballet of values in the secret of the underlying pointers, many verifications made by the interpreter... When something doesn't fit well , warning is given in the form of exception's messages.

Python has all the machinery under control

The only concern you must have is to think about the algorithm you want to achieve, and for that, knowing the data model is essential.

Welcome in the Python universe

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Warning

I don't consider myself as a very skilled Python developper, I'm just an amateur who had a lot of problems before understanding some essential things about Python.
All the above description is my personal views about the data model of Python. If any point is incorrect in this description, I will be happy to learn more about it if the teaching is done with developped argumentation.
But I underline the fact that this vision of things allows me to understand and to answer to a lot of tough problems and to achieve some tricky mechanisms that Python is capable of. So, all can't be false in this above description.

Answer 2

You should take a look at PEP8 documentation This describes the Python formatting and style.