Python __all__

Have you ever imported a Python file into another Python code and then used the variables from that file? In this case, all of the variables from the first file may be used in the second file. In this post, we'll examine one such Python module, __all__, which enables users to import certain variables rather than the complete set in a Python programme.

What does Python's __all__ mean?

In Python, __all__ is a list of strings that specify which variables must be imported into another file. Only after importing this file may you use the variables that are defined in that list in another file; otherwise, an error will occur when you try to use the other variables.

When the module is imported using the from module import * line, the names of the public objects that should be exported are specified in the list of strings called __all__.

Items that are not part of __all__ will not be allowed to be used in the importing module and will not be exported.

Consider the following instance.

In this case, the mymodule module's public interface is comprised of the fun1 function and the fun2 class, but the fun3 function is private and ought not to be accessed by outside code.

The only modules that will be imported in the current namespace when importing the module with the from my module import * line are fun1 and fun2.

Benefits of __all__ in Python

• Security Purpose: For security reasons, all of the variables from the first file can be used in the second file when importing data across Python files. The __all__ function in the first Python file can be used to specify the available variables if, for security reasons, we only want the second file to utilize a subset of the first file's variables rather than all of them.
• Use of the same variable name: Assuming that we have one variable, named XYZ, declared in the first Python file and that another Python program is calling the first Python file, all of the variables from the first file will be imported into the second file.

python __all__ best practices

A few guidelines should be followed while utilizing Python's __all__ attribute:

• Use _ _ all _ _ to clearly specify your module's public interface. This helps other developers understand which items are meant for internal use exclusively and which are meant for external use.
• The __all__ list should be concise and targeted. Only the objects in your module that are a part of the public API should be listed.
• Don't use imports with wildcards (from my module import*) in your code. Rather, use the import statement to import certain objects. This can assist in avoiding name clashes and make it obvious which objects are being utilized.
• Make use of __all__ together with thorough documentation. Every object's intended purpose and behavior in the public API should be well documented.
• Use the same language in all of your modules. Other developers will find it simpler to grasp how to utilize your code as a result.
• Keep in mind that __all__ only has an impact on import('mymodule') or import(*) wildcard imports. Even if an item is not imported entirely, it will be imported if a user imports it specifically from your module.

Example of python __all__ function

Here's a further illustration of using the __all__ variable in a Python module:

Explanation:

• Public Function (my_public_function): This function's goal is to be part of the open API. Its name is not underscore-prefixed, suggesting that it is intended for external usage.
• Private Function (_my_private_function): In Python, the underscore before the function name indicates that it is meant for internal usage only and is not part of the public API. This is a standard practice.
• Public Variable (my_var1): This variable's name does not include an underscore, indicating that it is a part of the public API and is accessible from the outside.
• Private Variable (_my_var2): The underscore before the name of this variable indicates that it is not a part of the public API and is only meant for internal usage.
• __all__ Attribute: This special characteristic consists of a list of names that are considered part of the public API. In this instance, it comprises the public variable (my_var1) and the public function (my_public_function).

Since my_public_function and my_var1 are included in everything in this example, other modules that import testmodule will be able to utilize them. Since they are not included in all, the _my_var2 and _my_private_function cannot be exported or used in other modules.

Advantages of python __all__ function

The use of the __all__ property in Python has many benefits:

• By explicitly specifying a module's public interface, other developers can quickly determine which components are only intended for internal use and which are intended for external use.
• Utilizing __all__ makes the code simpler to understand by providing a more coordinated association.
• Naming struggles with objects in the worldwide namespace can be limited by importing determined objects from a module rather than using trump card imports.
• Utilizing __all__ accomplishes clear documentation that makes sense of which articles are remembered for the public Programming interface and how to use them.
• When making changes to a module, it is easier to keep it backward compatible if only the internal objects are changed and the external interface is left alone.
• Program performance may improve by limiting the number of imported objects and avoiding wildcard imports. In this way, the program will only import what is needed.