One of the most frequent deviations of PEP 8 for other pieces of code is the variable naming, specifically for methods. The single underscore is simply a valid variable name thats sometimes used for this purpose. While you can call these methods directly ([10, 20].__len__() for example), the presence of the underscores is a hint that these methods are intended to be invoked indirectly (len([10, 20]) for example). They just look ugly to me, but maybe that's all the Java in my head. It actually makes readability easier if you know that functions have underscores and classes don't. Site design / logo 2023 Stack Exchange Inc; user contributions licensed under CC BY-SA. @rr PEP8 is a "Style Guide", and describes itself as a Convention, NOT a Standard. __double_leading_underscore: when naming a class attribute, invokes name mangling (inside class FooBar, __boo becomes _FooBar__boo; see below). AttributeError: module 'torch._six' has no attribute 'PY3', Significance of double underscores in Python filename. The Google Python Style Guide has the following convention: module_name, package_name, ClassName, method_name, ExceptionName, function_name, GLOBAL_CONSTANT_NAME, global_var_name, instance_var_name, function_parameter_name, local_var_name. Does a Michigan law make it a felony to purposefully use the wrong gender pronouns? Using the same name for variables which are in different functions? Safe to drive back home with torn ball joint boot? PEP stands for Python Enhancement Proposal, and there . Should I be concerned about the structural integrity of this 100-year-old garage? Take your time and play with some of the examples in this article. In some cases, the _-prefixed module written in C is the only implementation available. Is there a finite abelian group which is not isomorphic to either the additive or multiplicative group of a field? Why is it better to control a vertical/horizontal than diagonal? warning. Exception Naming. ____ means reserved Python name (both in filenames and in other names). (Python). You shouldn't invent your own names using the double-underscore notation; and if you use existing, they have special functionality. @AreTor what's important is to clearly mark what's public and what's not - not to make attributes "private". To learn more, see our tips on writing great answers. Triggers name mangling when used in a class context. Would a passenger on an airliner in an emergency be forced to evacuate? One class per file. more object oriented) However, that is the naming convention for C/C++ modules according to PEP8. Can we name python functions (not methods!) 15 Answers Sorted by: 1102 See Python PEP 8: Function and Variable Names: Function names should be lowercase, with words separated by underscores as necessary to improve readability. By clicking Accept all cookies, you agree Stack Exchange can store cookies on your device and disclose information in accordance with our Cookie Policy. What are the requirements for naming python modules? Assuming constant operation cost, are we guaranteed that computational complexity calculated from high level code is "correct"? This is briefly explained in the Modules tutorial. 1 The PEP-8 guide on module names states: Modules should have short, all-lowercase names. When an extension module written in C or C++ has an accompanying Raw green onions are spicy, but heated green onions are sweet. Looking for advice repairing granite stair tiles. It took me some research and editing to do it. Would you consider a constant static attribute a GLOBAL_CONSTANT_NAME ? Thats where _ is useful as a placeholder variable: Besides its use as a temporary variable, _ is a special variable in most Python REPLs that represents the result of the last expression evaluated by the interpreter. Asking for help, clarification, or responding to other answers. Thus following the Zen of Python's "explicit is better than implicit" and "Readability counts". What is the meaning of single and double underscore before an object name? Why a kite flying at 1000 feet in "figure-of-eight loops" serves to "multiply the pulling effect of the airflow" on the ship to which it is attached? Developers use AI tools, they just dont trust them (Ep. How to take large amounts of money away from the party without causing player resentment? 4 Answers Sorted by: 44 __.__ means reserved Python name (both in filenames and in other names). Confining signal using stitching vias on a 2 layer PCB. answered Apr 2, 2009 at 22:34 Stephan202 59.7k 13 127 132 3 Do most Python projects follow this convention? To subscribe to this RSS feed, copy and paste this URL into your RSS reader. From that, and the discussion here, I would deduce that it's not a horrible sin if one keeps using e.g. Site design / logo 2023 Stack Exchange Inc; user contributions licensed under CC BY-SA. For a manual evaluation of a definite integral. And I would also name the class Nib. What are the requirements for naming python modules? Connect and share knowledge within a single location that is structured and easy to search. Does the DM need to declare a Natural 20? First story to suggest some successor to steam power? In which cases one underscore is preferred (or needed) over two underscores? For example, __file__ indicates the location of Python file, __eq__ is executed when a == b expression is executed. attributes, variables, camelCase only to conform to Should I be concerned about the structural integrity of this 100-year-old garage? Therefore names like class or def cannot be used as variable names in Python. setattr, sizeof, str, subclasshook. Most editors have features that make this easy to do. Asking for help, clarification, or responding to other answers. Two underscores before and after name#. In Python, this style is generally deemed unnecessary because attribute and method names are prefixed with an object, and function names are prefixed with a module name. self._bar behaves the same wayit shows up on the class as _bar. Does "discord" mean disagreement as the name of an application for online conversation? Accelerator modules are described in PEP-399. Another example is the __eq__ method which provides equality comparison for a class. Question of Venn Diagrams and Subsets on a Book, Comic about an AI that equips its robot soldiers with spears and swords, dmitri shostakovich vs Dimitri Schostakowitch vs Shostakovitch. Prepending a single underscore (_) has some support for protecting module variables and functions (not included with import * from). But with the added flexibility, that you can allways add another class to a single file if it makes sense. PI cutting 2/3 of stipend without notice. Variable and constant with the same name in python. When did a Prime Minister last miss two, consecutive Prime Minister's Questions? The naming patterns we covered so far received their meaning from agreed upon conventions only. This document gives coding conventions for the Python code comprising the standard library in the main Python distribution. reduce_ex, repr, setattr, sizeof, str, subclasshook, weakref, _bar, foo, get_vars]. The only problem with using underscores is that you can't select a variable or function name with a double click you have to select the text manually. In the following code example Im unpacking a car tuple into separate variables but Im only interested in the values for color and mileage. Browse other questions tagged, Where developers & technologists share private knowledge with coworkers, Reach developers & technologists worldwide, The future of collective knowledge sharing, All in the spirit of "we're all consenting adults here" .
python - Why do some functions have underscores "__" before and after Scrutinized myself in attempts to find first sight understandable examples of complex constructions like list in the dictionary of lists where everything is an object. How can we compare expressive power between two Turing-complete languages? Is there a non-combative term for the word "enemy"? discouraged. Can module names in Python end with an underscore?
python - Naming convention for private modules - Stack Overflow Is there any political terminology for the leaders who behave like the agents of a bigger power? How should I call the module itself? How to resolve the ambiguity in the Boy or Girl paradox? General rule: If anything in Python is namend __anything__ then it is something special and you should read about it before using it (e.g. . There is PEP 8, as other answers show, but PEP 8 is only the styleguide for the standard library, and it's only taken as gospel therein. Underscores can be used in the module name if it improves readability. How to take large amounts of money away from the party without causing player resentment? Such a private module may be an accelerator module - a fast C implementation that exists alongside a slower pure-Python implementation of the same module (and which the pure-Python version tries to import everything from, so that the faster version is always automatically used if available). This module contains a class which contains GUI related methods. Making statements based on opinion; back them up with references or personal experience. Making statements based on opinion; back them up with references or personal experience. Browse other questions tagged, Where developers & technologists share private knowledge with coworkers, Reach developers & technologists worldwide, The future of collective knowledge sharing. This is also called name manglingthe interpreter changes the name of the variable in a way that makes it harder to create collisions when the class is extended later. Unlike wildcard imports, regular imports are not affected by the leading single underscore naming convention: I know this might be a little confusing at this point. It's not exactly global as it's in the scope of the class. For example, the _pydecimal module is a pure-Python implementation of the decimal module. Usually, this is because its functionality is imported and exposed by some "public", documented module. This is handy if youre working in an interpreter session and youd like to access the result of a previous calculation. Indicates special methods defined by the Python language. Are throat strikes much more dangerous than other acts of violence (that are legal in say MMA/UFC)? Is there a place that documents the use of leading. Not the answer you're looking for? Names surrounded by double underscores are "special" to Python. Developers use AI tools, they just dont trust them (Ep. Is Linux swap still needed with Ubuntu 22.04, Book about a boy on a colony planet who flees the male-only village he was raised in and meets a girl who arrived in a scout ship. Feel free to dismiss me as a heretic. As an example there might be about half a dozen or less instances of this naming scheme in the whole django codebase (mostly in the django.utils.functional package). __import__ or __file__. The only thing that seems to be universally true of these _-prefixed modules is that they're all implementation details of some documented, "public" module that doesn't have a _-prefix, and that you're supposed to use that module instead of directly importing stuff from the _-prefixed one. It is. Underscore, even though it's meant for C modules. Underscore after a variable name in Python, Why are python imports renamed with leading underscores, Leading underscore before the name of Python module. These are decidedly exceptions, though. Not as far as I know, but there are some things seen often: Thanks for contributing an answer to Stack Overflow! As the Python Style Guide points out, internal consistency matters most. ctypes vs _ctypes - why does the latter exist? The naming conventions of Python's library are a bit of a mess, so we'll never get this completely consistent - nevertheless, here are the currently recommended naming standards. I find it difficult to browse, despite folding. For classes: This is why I put together this little code example we can use for experimentation: Lets take a look at the attributes on this object using the built-in dir() function: [_Test__baz, class, delattr, dict, dir. Short answer: use a single leading underscore unless you have a really compelling reason to do otherwise (and even then think twice). Now, his competing app Spill isfunded. The module name changes and that results in a different module being imported. @IoannisFilippidis: If I had to put all classes for a module in a single file in the code sizes I normally manage, I would not even be able to open the file, collisions with other colleagues would skyrocket, and my boss would spit in my face (figuratively, that's it) for proposing it. Actually I use _ method names when I need to differ between parent and child class names. Site design / logo 2023 Stack Exchange Inc; user contributions licensed under CC BY-SA. Is it PEP8 compliant to import CamelCase as lowercase? Looking for advice repairing granite stair tiles, Scottish idiom for people talking too much. Find centralized, trusted content and collaborate around the technologies you use most.
Double underscore for Python method *argument*. First story to suggest some successor to steam power? When does the name mangling occur when using double underscores? Not the answer you're looking for? As for me - camelCase or their variants should become standard for any language. @SumitPokhrel it is PascalCase and camelCase, AFAIK. Why do most languages use the same token for `EndIf`, `EndWhile`, `EndFunction` and `EndStructure`? As far as I'm concerned I must have use this feature perhaps thrice in 15+ years, and even then I'm still not sure I really needed it. Find centralized, trusted content and collaborate around the technologies you use most. Do large language models know what they are talking about? Asking for help, clarification, or responding to other answers. @ThaneBrimhall In 2022, I am kicking everyone's butt who hands me newly written non-PEP 8 conformant code to review. In cherryPy for example, there are files like: How are they different? This is the name mangling that the Python interpreter applies. Not the answer you're looking for? In Python, the use of an underscore in a function name indicates that the function is intended for internal use and should not be called directly by users. rev2023.7.3.43523. They're listed in the Python Language Reference, section 3, "Data model". rev2023.7.3.43523. Does this change how I list it on my CV? Long answer: One underscore means "this is an implementation detail" (attribute, method, function, whatever), and is the Python equivalent of "protected" in Java. In the Python standard library, a leading underscore in a module name may denote an accelerator module: a module written in C that provides a more performant implementation of the pure Python version, for example _csv and csv.Accelerator modules are described in PEP-399.. Outside the standard library, the leading underscore conventionally denotes a private module, that is one that should not . By clicking Accept all cookies, you agree Stack Exchange can store cookies on your device and disclose information in accordance with our Cookie Policy. Do large language models know what they are talking about? There is also a convention that a name starting with an underscore is internal and should not be used by clients. rev2023.7.3.43523. It is presumably an unnecessary extended usage of applying the "single leading underscore" rule from the Style Guide for Python Code - Descriptive: Naming Styles: If anything, the said Style Guide actually is against using _single_leading_underscore.py in filename. module that provides a higher level (e.g. The new mangled method name, having a single leading underscore, is private. Developers use AI tools, they just dont trust them (Ep. Leading underscore before the name of Python module, mail.python.org/pipermail/tutor/2003-October/025932.html. E.g. Wait, why did we get that AttributeError when we tried to inspect the value of t2.__baz? This is what you should use for names that are not part of your class / module / package public API. Python packages should also have short, all-lowercase names, although the use of underscores is discouraged. Intuitively, I'd prefix the module name with an underscore. To learn more, see our tips on writing great answers. Generally not enforced by the Python interpreter (except in wildcard imports) and meant as a hint to the programmer only. Making statements based on opinion; back them up with references or personal experience. There is no single predominate style, although considering the volume of code that uses mixedCase, if one were to make a strict census one would probably end up with a version of PEP 8 with mixedCase. Connect and share knowledge within a single location that is structured and easy to search. Java's or C#'s (clear and well-established) naming conventions for variables and functions when crossing over to Python. Then I accessed the variable inside the context of a class named MangledGlobal.
Naming conventions - Python Modules - Python Studio How to resolve the ambiguity in the Boy or Girl paradox? Connect and share knowledge within a single location that is structured and easy to search. Naming conventions for function arguments in python, Python naming convention for variables that are functions. Er, because they do different things, as you yourself described? 4 parallel LED's connected on a breadboard. Is there a finite abelian group which is not isomorphic to either the additive or multiplicative group of a field? What does skinner mean in the context of Blade Runner 2049, Comic about an AI that equips its robot soldiers with spears and swords. The primary focus of PEP 8 is to improve the readability and consistency of Python code. How can we compare expressive power between two Turing-complete languages? For (a rather silly) example. I, personally, prefer this one for it's shortness and because everyone knows what it means.
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