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I'm writing a module which only contains functions. Is it good practice to put these inside a class, even if there are no class arguments and the __init__ function is pointless? And if so how should I write it?
There's no particular reason to force functions to go inside a class if there's no reason to make a class. A python sourcefile already provide a perfectly reasonable namespace for storing similar, related functions. The pypy implementation of the python programming language, for example, has many modules that don't have classes in them (for example, time).
You would want a certain data structure as a class, of course, but there are certain behaviors that are entirely independent of data structures, and putting them in a class would just add needless complexity.
It is good to build modules that contain a class for better organization and manipulation depending on how big the code is and how it will be used, but yes it is good to get use to building classes with methods in them. Can you post your code?
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So I have a Python program where I use classes for certain areas to stop the need for global variables. However, I still use straight up functions in other areas of the program. Would it be good practice to turn all of my code into classes like an OOP or is a mix ok. I'm also wondering what UML diagrams work well for a mix because I'm not sure if a class or sequence diagram will work.
Usually that's something for the team to decide, generally it's considered a good practice not to mix functions and classes in a single module. Most UML diagram tools for Python work fine with plain functions. A class in this case is your module and it has only one instance.
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I have a python object that represents a connection to a rest api with a large number of endpoints. I need to come up with a strategy to organize hundreds of method calls (right now I am using prefixes on the methods). I would also like to break up the files if that's possible.
I am working in python 2.7
Two give more clear questions -
1) Is it possible to split an object into multiple files in some sort of effective manner in python? Specifically without introducing more complexity?
2) Is it possible to make "submodules" for lack of a better phrase, so
my_rest_api.users.create
rather than
my_rest_api.users_create
You can implement the groups as mixins. For example like this:
user_actions.py
class UserActions:
def user_create(...): ...
the_api.py
from . import user_actions
class TheApi(UserActions, ItemActions, OtherActions, ...):
# common functionality goes here
Then you can call the_api_instance.user_create(...) once you have an object created.
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As the title suggests, I'm interested in the best (perhaps the most Pythonic way) to structure a program which uses many global variables.
First of all, by "many", I mean some 30 variables (which may be dictionaries, floats or strings) which every module of my program needs to access. Now, there seem to be two ways to do this:
define the "global" variables in seperate modules
use an object oriented approach
The advantage of using an object oriented approach is that I can have many instances of some main class initialized, and perhaps compare different values (results of some analysis, for example) later on.
I already have a program written, but basically it breaks down to one class with some 30 or so attributes. Although it works fine, I'm aware this is a pretty messy way to do this.
So, basically, is I use OOP approach, I would perhaps need to break my main class down to a few subclasses, every one of which stores specific logically related variables.
Any suggestions are welcome.
P.S. Just to be concrete about what I'm trying to do: I have a FEM-solver which needs to store structure info, element and node data, analysis result data, etc. So, I'm dealing with a lot of data types most of which are connected in some way.
Unfortunately, as was hinted at in the comments, there is no "Pythonic" way to do this. Having a large number of global constants is just fine - many programs and libraries do this. But in the comments, you've specified that all of your globals are being modified.
You need to take your program's architecture back to the drawing board. Rethink the relationships between your program's entities (functions, classes, modules, etc). There has to be a better way to organize it.
And by the way, it also sounds like you're getting close to using the God Object Antipattern. Use some of the advice in this SO question to refactor your massive class that has it's fingers all over your program.
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Sometimes, when looking at Python code examples, I'll come across one where the whole program is contained within its own class, and almost every function of the program is actually a method of that class apart from a 'main' function.
Because it's a fairly new concept to me, I can't easily find an example even though I've seen it before, so I hope someone understands what I am referring to.
I know how classes can be used outside of the rest of a program's functions, but what is the advantage of using them in this way compared with having functions on their own?
Also, can/should a separate module with no function calls be structured using a class in this way?
A module is preferred when it is a collection of pure functions i.e. no shared state like module level variables. A big class is often used when there are multiple functions operating on a shared state.
In Python scripts, you will often see the pattern of the main function being just the instantiation of a class and calling a method for e.g youtube-dl. This is done for various reasons:
Can instantiate multiple objects without mixing state. It is easier to make it threadsafe.
Classes can be inherited or composed (for e.g. see BaseHTTPRequestHandler
Classes have more features than modules like constructors, iteration support etc.
In general, classes offer more power with slight added complexity. Some people prefer functions for simplicity esp in the case of one-time scripts. The tradeoff is upto the developer and both are valid options in Python.
A program often has to maintain state and share resources between functions (command line options, dB connection, etc). When that's the case a class is usually a better solution (wrt/ readability, testability and overall maintainability) than having to pass the whole context to every function or (worse) using global state.
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I have a huge C file (~100k lines) which I need to be able to parse. Mainly I need to be able to get details about individual fields of every structure (like field name and type for every field in the structure) from its definition. Is there a good(open source, which i can use in my code) way to do this already? Or should I write my own parser for this. If I have to write my own, can anyone suggest a good place to start? I have never worked with python before.
Thanks
Take a look at this link for an extensive list of parsing tools available for Python. Specifically, for parsing c code, try the pycparser
The right way to do this is almost certainly to interface with the front-end of an existing compiler, such as gcc, then work with the intermediate representation, rather than attempting to create your own parser, in any language.
However, pycparser, as suggested by Dhara might well be a good substitute, and definitely better than any attempt to roll your own.