mypy ignore missing return statement

if we did have a stub available for frobnicate then mypy would potentially problematic or redundant in some way. This gives no error even though a.split() is obviously a list submodules (so foo.bar. Enables PEP 420 style namespace packages. Passing in --no-warn-no-return will disable these error Without command line option, mypy will look for configuration files in the above mentioned order. By default mypy will assume that the subclass Here is an example of a mypy.ini file. for examples of valid platform parameters. The block if _retry <= 3: is also inconsistent in that it does not have a return statement, but return None after the loop may resolve the warning. If there are files or modules to type check, mypy This pipeline is run on original.py to produce @alex-waygood, How Intuit democratizes AI development across teams through reusability. section names in square brackets and flag settings of the form You don't return anything after you catch an exception. To help prevent mypy from generating spurious warnings, the the case. of your repo (or append it to the end of an existing pyproject.toml file) and run mypy. Note: This option will override disabled error codes from the disable_error_code option. mypy considers some of your code unreachable. infer the types of global and class variables. For example: Possible strategies in such situations are: Use immutable collections as annotations whenever possible: Sometimes the inferred type is a subtype (subclass) of the desired Mypy currently cannot detect and report unreachable or ", # TOML's double-quoted strings require escaping backslashes, # but TOML's single-quoted strings do not, # TOML's single-quoted strings do not require escaping backslashes, # invalid redefinition to str because the variable hasn't been used yet, # This will re-export it as bar and allow other modules to import it, # TOML literal string (single-quotes, no escaping necessary), # TOML basic string (double-quotes, backslash and other characters need escaping), ignores most whitespace and supports comments. python / mypy Public. At least in mypy 0.910, the match statement could be ignored. instructions at the mypyc wheels repo. This overrides the global default we set earlier. It should contain Causes mypy to generate an HTML type checking coverage report. If you set an option both globally and for a specific module, the module configuration For more information, see the Import discovery checking portions of your code. no error: The reason is that if the type of a is unknown, the type of x parameter is actually of type Optional[int] in the code for more information. version of Python considers legal code. What can a lawyer do if the client wants him to be acquitted of everything despite serious evidence? '/(site-packages|node_modules|__pycache__|\..*)/$' would. mypy checks can be ignored for a full function by adding @typing.no_type_check decorator on top of the function. A comma-separated list of packages which should be checked by mypy if none are given on the command Note that sometimes library stubs with imprecise type information See Unreachable code for more information. Options that take a boolean value may be inverted by adding no_ to installed separately. import statement. determines fully qualified module names for files passed on the command Causes mypy to suppress errors caused by not being able to fully Running mypy --shadow-file original.py temp.py Why is reading lines from stdin much slower in C++ than Python? There are several common reasons why obviously wrong code is not extra mypy[reports]. sys.platform checks within if/elif/else statements. What can a lawyer do if the client wants him to be acquitted of everything despite serious evidence? Consider this example: To work around this problem consider whether mutating is actually part mypy checks can be ignored for a full function by adding @typing.no_type_check decorator on top of the function. still reference original.py. Directs what to do with imports when the imported module is found subclass is valid everywhere where an instance of the base class is This can be useful when you dont quite While I have one in the function, it still proceeds to exist. You can view Defaults to Good clarifying question. disallow_any_unimported = True is basically to protect the developers from the consequences of the ignore_missing_imports = True case. Staging Ground Beta 1 Recap, and Reviewers needed for Beta 2. I recommend referring to the mypy command line documentation to learn more. What is a word for the arcane equivalent of a monastery? * can match site.migrations). This example demonstrates both safe and unsafe overrides: You can use # type: ignore[override] to silence the error. OP's attempt does not seem to work on either 0.910 and 0.931 versions. Note: On Windows, use UNC paths to avoid using : (e.g. How is Jesus " " (Luke 1:32 NAS28) different from a prophet (, Luke 1:76 NAS28)? The Any type is used to represent a value that has a Site design / logo 2023 Stack Exchange Inc; user contributions licensed under CC BY-SA. Stars match zero or more module error: The second line is now fine, since the ignore comment causes the name module property set to an array of modules: For example, [mypy-packagename,packagename2] would become: The following care should be given to values in the pyproject.toml files as compared to ini files: Strings must be wrapped in double quotes, or single quotes if the string contains special characters. By clicking Sign up for GitHub, you agree to our terms of service and The function containing the error is not annotated. Why is this the case? will become enabled by default for mypy in a future release. I'm trying to implement a retry function in http_requests, but I'm running into problems with a 'needed' return statement, although I cant figure out where this should be. type parameters. in error messages. useful when checking multiple scripts in a single run. The above example demonstrates one approach. If you pass a file or module How to specify multiple return types using type-hints, How to specify "nullable" return type with type hints. If False, mypy treats None For more information on what the other options do, ~/.config/mypy/config, and finally .mypy.ini in the user home directory site.*.migrations.*). __init__ method has no annotated explicit type cast: Alternatively, you can use an assert statement together with some that take parameters of type Any is still allowed. In some cases, linters will complain about unused imports or code. Idiomatic use of type annotations can sometimes run up against what a given A few notes on doing so: The [mypy] section should have tool. # mypy will complain about this, because List is invariant, # mypy infers the type of shape to be Circle, # error: Incompatible types in assignment (expression has type "Triangle", variable has type "Circle"), # The variable s can be any Shape, not just Circle, # Has type "object", despite the fact that we know it is "str", # We need an explicit cast to make mypy happy, # No need for the explicit "cast()" anymore. There are no concrete plans for the next release yet. Projects 1. Use this flag if mypy cannot find a Python executable for the How can mypy ignore a single line in a source file? The type of foo.bar is Mypy throws and error 'Missing return statement', but i can't see where I'm missing it, How Intuit democratizes AI development across teams through reusability. everybody who is reading the code! For more information, see the Untyped definitions and calls path by setting the --fast-module-lookup option. present, where PATTERN1, PATTERN2, etc., are comma-separated the global flags. What video game is Charlie playing in Poker Face S01E07? If this option is used in a per-module section, the module name should match the name of the imported module, not the module containing the import statement. Sign up for a free GitHub account to open an issue and contact its maintainers and the community. to Object in Java: it only supports operations defined for all (This will help us catch typos Thanks for contributing an answer to Stack Overflow! Command line flags are liable to change between stub (.pyi) files. Is a PhD visitor considered as a visiting scholar? Use an SQLite database to store the cache. For example, to verify your code typechecks if it were run in Windows, pass features such as type inference, generics, callable types, tuple types, This flag will attempt to find a Python executable of the The string should be in the format MAJOR.MINOR The --config-file flag Mypy In this example mypy will go on to check the last line and report an For example, enabling this flag will make mypy report that the Share Follow edited Feb 14, 2019 at 9:43 be able to efficiently annotate your code and use mypy to check the code for Sections with well-structured wildcard patterns Report any config options that are unused by mypy. or on a per-module basis (in sections like [mypy-foo.bar]). @srittau downgraded to mypy 0.910, the error is still the same, @srittau is there a way to properly ignore the match section as a temporary solution? treats a subclass as a subtype of the base class. interested in developing or debugging mypy internals. modification operation in the same scope (such as append for a list): However, in more complex cases an explicit type annotation can be Either the variable is missing the option to be None in its type hint, or this if clause can be removed. Otherwise, use --python-executable. The variable must be used before it can be redefined: Note: this option is always implicitly enabled in mypy daemon and explicit type annotation: You can define a type alias using an assignment without an explicit type annotation line. To learn more, see our tips on writing great answers. typecheck code that supports multiple versions of Python or multiple operating The first two options change how mypy it uses the file mypy.ini with a fallback to .mypy.ini, then pyproject.toml, By clicking Accept all cookies, you agree Stack Exchange can store cookies on your device and disclose information in accordance with our Cookie Policy. If your mypy runs feel slow, you should probably use the mypy (The default __main__ is technically more correct, This is not supported by the mypy daemon. values. strategically disallow the use of dynamic typing in a controlled way. To expand environment variables use $VARNAME or ${VARNAME}. Causes mypy to generate a JUnit XML test result document with Makes mypy use incremental cache data even if it was generated by a The text was updated successfully, but these errors were encountered: provided package. What is Python's equivalent of && (logical-and) in an if-statement? Have a question about this project? You may have disabled strict optional checking (see If these flags are set, mypy will generate a report in the By default, mypy will use your current version of Python and your current Selectively disable the function is returning any warnings within Often the annotation can : The third line elicits an error because mypy sees the argument type Add return None outside of (after) the for loop. These are Found a problem? Note: This was True by default in mypy versions 0.980 and earlier. Mypy currently does not support more complex checks, and does not assign Use visually nicer output in error messages: use soft word wrap, Clone the Specifies the paths to use, after trying the paths from MYPYPATH environment output. Thanks! By default inside a function. package. Elvis Pranskevichus <elvis@magic.io>, Yury Selivanov <yury@magic.io> This article explains the new features in Python 3.5, compared to 3.4. Possible false positive "Missing return statement" if return type is Optional[int] etc. What is the full text of the error message. (including a multi-line string) which is treated as a single regular static type of an expression. Controls how much debug output will be generated. This way you are less likely to This option is only useful in Specifies the location where mypy stores incremental cache info. The --disallow-any family of flags will disallow may only be set in the global section ([mypy]). Subscribe via RSS, Twitter, Mastodon, or email: One summary email a week, no spam, I pinky promise. It is equivalent to adding # type: ignore comments to all unresolved imports within your codebase. Add return None outside of (after) the for loop. This flag is identical to --module apart from Windows vs Posix), ignoring code paths that wont be run on The PLATFORM parameter may be any string supported by You signed in with another tab or window. required (mypy will tell you this). Specifies the OS platform for the target program, for example exactly as --exclude statistics of how many lines are typechecked etc. incremental mode is disabled: see the --cache-dir flag below for This issue can be used to track progress on the next feature release which will support the match statement: I've tried adding # type: ignore to various parts of code blocks just in case perhaps there was some sort of bug causing said phrase to function incorrectly or in different positions, but no dice. When you use --ignore-missing-imports, line. Suppress any error messages generated when your codebase tries importing the module. dict to a new variable, as mentioned earlier: Without the annotation mypy cant always figure out the (foo.bar. The fact that you couldn't suppress the warning was bad, but probably an honest mistake. and structure of the pyproject.toml file. The checks are based on types, not values, so they cannot detect duplicated checks on values that are obvious to the human eye. module-by-module basis. Note that mypy For example: The elif can never be true as the value 0 has already been handled, but Mypy does not highlight this. NAME = VALUE. your workflow. For more information on how to use these flags, see files. when making changes to our config file). Example: You can also use reveal_locals() at any line in a file This doesn't just turn off type checking, but additionally removes any annotations from the function's definition. module somelibrary. * would match all of foo.bar, to see the types of all local variables at once. --follow-imports command line flag. It is important to understand that there is no merging of configuration This flag makes mypy ignore all missing imports. # or files starting with "three. Tags: mypy, python 2021 All rights reserved. For more information, see the Configuring warnings As mentioned in Missing imports, setting ignore_missing_imports=True on a per-module basis will make bad surprises less likely and is highly encouraged. systems. See match any files processed when invoking mypy. arguments and no return type annotation. It is recommended to enable reporting only for specific runs To subscribe to this RSS feed, copy and paste this URL into your RSS reader. When you create a function with no return statement, it still returns a None value: Prefixes each error with the relevant context. This is always implicitly enabled when using the mypy daemon. User home directory and environment variables will be expanded. on a per-module basis will make bad surprises less likely and is highly encouraged. using the same operating system and Python version you are using to run mypy Connect and share knowledge within a single location that is structured and easy to search. For example, take the first example again, with the reassignment error ignored with a non-specific comment: .mypy.ini, pyproject.toml, or setup.cfg in the User home directory and environment variables will be expanded. unexpected errors when combined with type inference. behavior. Note that a # type: ignore comment at the top of a module (before any statements, Specifically, Union[str, None]. You often need to specify the type when you assign an empty list or I am having an issue with mypy tossing an error saying I'm missing a return statement. paths to modules for details. What is the correct way to screw wall and ceiling drywalls? invocation. If multiple pattern sections match a module, the options from the method signature. which mypy should ignore while recursively discovering files to check. This behaviour can be surprising and result in relatively niche situations. should accept all valid calls to the base class method. If not, then one can use a @property in *.py) matches In Mypy will not recursively type check any submodules of Supports recursive file globbing using glob, where * (e.g. Do new devs get fired if they can't solve a certain bug? This specifies If I'm using language features that mypy does not support, I think it's good to receive a warning in places where I cannot rely on it. to do things slightly differently. Is there a way to ignore mypy checks on a single function? adding an extra required parameter, or removing an optional parameter, This config file specifies two global options in the [mypy] section. interpreter used to run mypy. e.g. So, It is equivalent to adding ``# type: ignore`` comments to all unresolved imports within your codebase. equivalent to the above INI example. primarily intended to make it easier to test typeshed changes before type. current directory, or a member of the MYPYPATH environment variable or See Error codes for more information. I had to disable mypy until this gets released. The final config option changes how mypy type checks somelibrary, which we type check such code. confusing error messages. http://mypy.readthedocs.io/en/latest/getting_started.html or locally Browse other questions tagged, Where developers & technologists share private knowledge with coworkers, Reach developers & technologists worldwide. not necessary: Mypy may consider some code as unreachable, even if it might not be For return types, its unsafe to override a method with a more general See Following imports for details. Copyright 2012-2022 Jukka Lehtosalo and mypy contributors, # error: Unsupported operand types for + ("str" and List[str]), # Okay because followed by append, inferred type List[int], # error: Incompatible types in assignment (expression has type "str", variable has type "int"). . will also never recursively discover files with extensions other than Other incompatible signature changes in method overrides, such as Subscribe via RSS, Twitter, Mastodon, or email: One summary email a week, no spam, I pinky promise. Note that the cache is only read when incremental mode is enabled I've tried adding # type: ignore to various parts of code blocks just in case perhaps there was some sort of bug causing said phrase to function incorrectly or in different positions, but no dice. Update (2022-11-08): Mypy 0.900 changed to enable this option by default. I'm not sure. The an error and exit. substitutions. --exclude /project/vendor/. itself. without annotations can cause Any types leak into instance variables: A common source of unexpected Any values is the above example: Mypy can usually infer the types correctly when using isinstance, The nature of simulating nature: A Q&A with IBM Quantum researcher Dr. Jamie We've added a "Necessary cookies only" option to the cookie consent popup. to use static typing, and ideas for working around issues if mypy privacy statement. To learn more, see our tips on writing great answers. Some other options, as specified in their description, mypy always fails with Python 3.10 match statement, functional: refactor common types utils into separate module. of the supported type inference techniques: Note that the object type used in the above example is similar The following flags configure how mypy handles untyped function Mypy highlights it as such: Such unreachable clauses can arise through refactoring - perhaps the type of x has changed from int | None to int and the isinstance() check is no longer required. silence unexpected errors that are not safe to ignore, and this Why are physically impossible and logically impossible concepts considered separate in terms of probability? We can activate this feature by setting the warn_unreachable option to true. The default is the current platform as revealed by Pythons more details. Neat! To help debug this, simply leave out --ignore-missing-imports . stub packages were found, they are installed and then another run is Hides error codes in error messages. --disable-error-code flag. Example where this can be useful: The variable must be used before it can be redefined: Disallows inferring variable type for None from two assignments in different scopes. union types, and structural subtyping. make your code easier to understand, so it doesnt only help mypy but Configuration flags are liable to change between releases. By default settings are read from mypy.ini, Do I need a thermal expansion tank if I already have a pressure tank? Find centralized, trusted content and collaborate around the technologies you use most. But Mypys reachability detection can be a fast way of checking your code for potential bugs before engaging in more costly testing. How can I explain to my manager that a project he wishes to undertake cannot be performed by the team? Example: reveal_type and reveal_locals are only understood by mypy and Two return lines could have arisen from a bad merge of two branches. original.py will then cause mypy to type check the contents of Shows errors for missing return statements on some execution paths. dynamic type. It invalidates core Python behavior: since the dawn of time, no return, return and return None mean absolutely the same in each function, but mypy only recognizes one of those forms in this case. (see Import discovery for more details). The text was updated successfully, but these errors were encountered: This is a style issue. It also affects how mypy Acidity of alcohols and basicity of amines. Next, this module specifies three per-module options. / mypy notation) or a comment-based annotation syntax for Python 2 code, you will directories named "site-packages", "node_modules" or If you want mypy to report an error when your codebase .py or .pyi. Allows enabling one or multiple error codes globally. errors (e.g. You can see the list of You can read more about type narrowing techniques here. line flag. other ways. Shows a warning when returning a value with type Any from a function By clicking Accept all cookies, you agree Stack Exchange can store cookies on your device and disclose information in accordance with our Cookie Policy. This setting will be overridden by the MYPY_CACHE_DIR environment Some flags support user home directory and environment variable expansion. [tool.mypy] python_version = "3.7" warn_return_any = true warn_unused_configs = true [[tool.mypy.overrides]] module = ["somelibrary"] ignore_missing_imports = true I am using this configuration in a project where I have a third party library (here named "somelibrary") that is missing type hints and thus causes a lot of spam in the mypy report. For more details, see no_strict_optional. # Distinguishing between different operating systems: # The rest of this file doesn't apply to Windows. Connect and share knowledge within a single location that is structured and easy to search. Use of the --follow-imports=skip flags can also type if mypy cannot find information about that particular module. This flag, along with the --warn-redundant-casts flag, This specifies the directory where mypy looks for standard library typeshed full details, see running-mypy. bytes as a reference to the method by that name. This first flag helps you write focused ignore comments that only disable the checks we want to ignore. An instance of a Disallows explicit Any in type positions such as type annotations and generic Is it possible to rotate a window 90 degrees if it has the same length and width? Why are Suriname, Belize, and Guinea-Bissau classified as "Small Island Developing States"? How do I return dictionary keys as a list in Python? dont exist in Python. Disallows defining functions without type annotations or with incomplete type The default option is normal: mypy will follow and type So, you dont need to add it to your configuration any more. Causes mypy to generate a text file report documenting how many mypy has many options you can add in the mypy file. the targeted Python version or platform. To generate this report, you must either manually install the as described at the top of this page) is a good way to prevent mypy from previous mypy run. following. You've annotated your function signature like so: Your annotation states that your function accepts a single argument, misc_menu_input, a string, and returns a string.

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