Python modules are an essential part of Python projects and form a significant aspect.
Python is incomplete without these modules, modules are of different types, provide different functionality, and have their usability. In this article, we will understand and study how to retrieve a Python module’s path.
We will be extensively covering the how, why, and what of this topic in this article.
A Python module is nothing but another Python script that has particular code that includes various Python definitions and statements.
These statements and definitions are built in a way that they provide some functionality that is to be used later on. When we need to perform that specific functionality, we can simply import that module into our current file.
To get a better understanding and take a deep dive into what Python modules are.
Importance of Understanding Module Paths
Since we have a piece of good knowledge about Python modules, the question arises that why exactly we need to worry about their path, as we’re only concerned about the functionality that the module provides most of the time.
Below mentioned are a few reasons why it is important to know the paths to Python modules:
Firstly python needs to find the module in the machine to import it; hence it is required to know the path to the module through which the Python interpreter can locate the module.
If there arises a situation where there is a bug or some error in the function that the module performs, we need to be able to find the module and navigate to it and fix it explicitly, and even this can become important for us to know the path to the module.
When we are managing different versions of the same module, it becomes difficult to differentiate or identify between the two. Hence the path of these modules is being used as a differentiator; therefore, even in this scenario, it becomes necessary to know the path.
Understanding Python Module Paths
What are Module Paths?
Path, in this sense, means the exact location where the module is stored in the machine or a path that could be used to navigate through and find the desired module.
As we know, that module path is nothing but the address of that module in our machine, we would not be able to perform any operation on file of which we do not have the address. So the module path becomes an essential part of a module which is nothing by a file.
As different files have various types of attributes, the path is also another attribute that is associated with the module, which gives us an exact idea about the location of the module so that we can easily navigate to it and perform operations on it.
The ‘sys’ Module and its Significance
The ‘sys’ module becomes very important in terms of retrieving and managing module paths. It is a built-in module that performs various functionalities related to the system.
To start working with sys, you will first have to import it using the command given below.
Some ways in which the sys module becomes important are as below:
The ‘sys’ module has an attribute which is the ‘sys.path’ attribute which is nothing but a list of paths in which Python searches for modules when imported.
The result of ‘sys.path’, which is a list of directories, can be easily modified, which provides flexibility which using and importing modules.
The above code is another use case of the sys model in which we extend the path attribute to add a new path to the list of directories.
One of the main features is that, when working in a virtual environment, the sys module will always give first preference to the modules which are installed inside the virtual environment
Retrieving Module Paths using Built-in Functions.
Since we have a brief idea about what modules are and what module paths are, and the importance of knowing them and having access to them, let’s begin with learning methods by which we can retrieve the paths:
Using ‘__file__’ attribute
This is a built-in attribute that throws the path from where the module was loaded. Typically works only with modules. A tool used to find the location of where the module exists in our system.
How does it work?
Firstly for this example, I will be creating a module that is nothing but a Python file with a ‘.py’ extension. The IDE that I will be using is Pycharm.
The choice of IDE is wholly based on your set-up, and the code below will not change irrespective of the IDE.
This is a very simple module that has a basic function, which returns a string that asks your age.
Now I will be trying to import this module that we just created in our main.py file.
As you can see, once I run the above code and call the function, the module we just imported behaves like any other module and performs the specified task.
Now to find the path of this module, we could simply run the above code, and we will get the path as shown in the image below.
A quick note on this method that is at there is any built-in module that does not have this attribute, the output will throw an “AttributeError”.
Using the ‘inspect’ module
A built-in module that helps in extracting valuable information about Python elements such as modules, classes, functions, etc. It has various functionality, but the one we are interested in is its ability to extract information about modules.
Let’s begin by seeing it in practice.
How does it work?
To begin with, as it is a module, we will first need to import the ‘inspect’ module, and we will be using the same module that we have created in the above example for demonstration purposes.
To import the ‘inspect’ module, use the below command.
I have imported our previously used module and I will be using the below code to get information about the module.
path_to_module = inspect.getfile(sample)
If you run the above code without any errors, you will have a similar output to what is shown in the below image.
As you can see in the output window, the program has returned the path to my module.
The above was just one method of the inspect module through which you can get the path to a module, but there are various other functions that also perform the same functionality and can be used when and where required.
The commands to use different methods are given below:
path_to_module = inspect.getmodule(<module_name>)
path_to_module = inspect.getsourcefile(<module_name>)
Using the ‘os’ module
The ‘os’ model is an important module for Python when it comes to working with paths. This module provides an interface between the Python script and the operating system. Manages modules and handles their path at the operating system level.
How does it work?
The most important method of the os module when it comes to finding paths is the ‘os.path’ method. We will be seeing this method in practice.
For this example as well, I will be using the same module that I created earlier and then try to extract its path using the os.path method.
Firstly to start using the os module, we will have to import it using the command given below.
path_to_module = sample.__file__
os_path = os.path.abspath(path_to_module)
Once we have imported the os module, we can use the above code, and if you do it without any errors, you will have the same output as shown in the below image.
The above code is very simple; for this example, I have used the ‘__file__’ attribute in combination with the os.path method, but you could use it in the same way with the methods of the inspect module.
Benefits of using the ‘os’ module.
As seen in the above example, we understood that the os.path method needs to be used in combination with the other methods to execute properly, then why exactly do we use it?
The main reason is that the os.path method provides us with cross-operating system compatibility because, as we have discussed above, the os module works at the operating system level.
This advantage alone is enough to make the os module a very handy tool for extracting the module’s path.
Advanced Techniques for Path Retrieval
Handling Challenges with Virtual Environment
A virtual environment is a virtual system that is created when we work on Python project. To take a deep dive into Python virtual env, please read through this link.
Extracting the Module path is difficult in the case of a virtual environment, as the actual module and the module inside the virtual module create a conflict.
We have to very carefully tackle this situation so that we don’t retrieve the path to the actual module and make our virtual environment-specific changes to the actual module.
Let’s see a way through which we can handle this situation
You can use the below code to retrieve the path to a module inside a virtual environment.
module_object = sys.modules[name_of_module]
module_path = module_object.__file__
module_path = os.path.abspath(module_path)
module_object = importlib.import_module(module_name)
module_path = module_obj.__file__
module_path = os.path.abspath(module_path)
We have done nothing new in the above code, all we did is just compile everything that we learned till now in this article, and we’ve placed it inside a try and except block.
A sample use case of the above code is as follows.
module_path = get_path_to_module('my_module')
print("Path of the module:", module_path)
print("Module not found.")
Avoiding Hard-coded Paths
Hard-coding anything is always considered a bad practice.
As whenever we need to make changes, we will have to manually go back and make those changes, so in case we need to add the modules path as the value in our program, it would not be a good practice use manually type in the path to that module.
Consider a situation where the location or the path of the module changes, and we encoded the previous path manually; such a situation may lead to a fatal error.
Hence using the above methods to retrieve a module’s path would be great practice as the above methods are able to handle these changes in the module’s path.
Cross Platform Consideration
While writing code, we must make sure that we are writing code that is capable of handling platform changes because, at times, it happens that when we write a specific code on a particular, it faces issues when running on some other machine. For this purpose, the ‘os’ module becomes an excellent choice.
To conclude, let’s recollect whatever we have covered so far; we began with understanding what modules are and why knowing their paths is important.
Once we figured out about modules, we went ahead and learned the different methods through which we retrieved the module’s path.
We went through the different methods, what are their pros and cons, and how they work. Lastly, we even took an overview of some best practices that we can follow to implement the above methods.