mypy-upgrade 0.0.1b3

automatic error suppression for mypy

mypy-upgrade

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Table of Contents

• What is mypy-upgrade?
• Features
• Basic Usage
• Recommended Mypy Flags
• Command-Line Options
• Quick Start
• Known Limitations
• Similar Projects

What is mypy-upgrade?

mypy-upgrade is a command-line utility that provides automatic error suppression for mypy (analogous to pyre-upgrade and pylint-silent).

Given a type checking report from mypy, mypy-upgrade will silence the listed errors using error suppression comments. For example, with the following output from mypy:

package/subpackage/module.py:13: error: Incompatible default for argument "filename" (default has type "None", argument has type "str") [assignment]

mypy-upgrade will place a # type: ignore[assignment] # FIX ME comment at the end of line 13 in package/subpackage/module.py. If error codes are not present in the mypy report (e.g., the --hide-error-codes flag is set when mypy was invoked), then a non-specific # type: ignore # FIX ME comment will be added instead.

Features

• Removal of unused type: ignore comments

• Replacement of blanket type: ignore comments with error code-specific comments

• Support for suppressing multiple mypy errors per-line

• Preservation of existing in-line comments

• Optional inclusion of mypy error description messages

Basic Usage

There are two idioms for invocation. To silence all errors in a package, one can:

1. pipe mypy's output directly to mypy-upgrade

    mypy --strict -p my_package | mypy-upgrade
   

2. create a mypy type checking report text file

    mypy --strict -p my_package > mypy_report.txt
   

   and then pass the file to mypy-upgrade

    mypy-upgrade --report mypy_report.txt
   

Command-Line Options

You may want to include the error messages provided by mypy in the suppression comments so that you can fix them later. You can do so using the -d (or --description-style) option

mypy-upgrade --report mypy_report.txt -d full -p package

You can also customize the "fix me" message placed after the error suppression comment using the --fix-me option

mypy-upgrade --report mypy_report.txt --fix-me "FIX THIS" -p package

To selectively silence errors in packages and modules, use the -p (--package) and -m (--module) options along with the fully qualified module/package name, respectively:

mypy-upgrade --report mypy_report.txt -p package1 -p package2 -m package1.module1 -m package2.module2

Similarly, to selectively silence errors in files and directories, pass them in as positional arguments:

mypy-upgrade --report mypy_report.txt path/to/my_package/ path/to/a/module.py

For a full list of all options and their descriptions, run

mypy-upgrade --help

Recommended Mypy Flags

To enable all checks utilized by mypy-upgrade to silence as many errors as possible, the following flags should be set when creating the type checking report to pass to mypy-upgrade:

• --show-absolute-path

  • Required if running mypy-upgrade in a separate directory than mypy

• --strict

  • Enables mypy-upgrade to silence all possible mypy errors (see Known Limitations for exceptions)

• --show-column-numbers

  • Allows for more precise treatment of certain type error edge cases (e.g. type checking errors before the start of multiline strings)

• --show-error-codes

  • Ensures that error-code specific comments are added instead of blanket type: ignore comments

• --warn-unused-ignores

  • Ensures that unused type: ignore comments are removed

• ignore-without-code

  • When used with --show-error-codes, permits mypy-upgrade to replace existing type: ignore comments with code-specific type: ignore comments (enable from the command line with the mypy option --enable-error-code)

Quick Start

mypy-upgrade can be installed via pip.

python3 -m pip install mypy-upgrade

If you want to run the latest version of the code, you can install from the repo directly:

python3 -m pip install -U git+https://github.com/ugognw/mypy-upgrade.git@development
# or if you don't have 'git' installed
python3 -m pip install -U https://github.com/ugognw/mypy-upgrade/tree/development

Known Limitations

The following limitations derive mainly from Python syntax issues and are unable to be handled by mypy-upgrade. If you can't resolve the error directly, please consider refactoring to permit error suppression.

• Type errors on lines ending in line continuation characters or within multiline f-strings

  • Comments are not permitted within multiline strings or following line continuation characters and Mypy only recognizes inline type: ignore comments (see #3448)

  • Pre-formatting your code with a PEP8 adherent formatter (e.g., black) to replace such lines with parentheses is recommended.

Similar Projects

If this doesn't fit your use-case, maybe one of these other projects will!

• geo7/mypy_clean_slate: mypy reports are generated internally in --strict mode; includes support for suppressing multiple errors on a single line; an inspiration for much of mypy-upgrade's implementation

• whtsky/mypy-silent: relies solely on typer + the standard library; includes support for removing unused type: ignore comments but no support for suppressing multiple errors on a single line; another inspiration for much of mypy-upgrade's implementation

• patrick91/mypy-silent: a fork of whtsky/mypy-silent with support for suppressing multiple errors on a single line (on the feature/multiple-errors branch)

• uptickmetachu/mypy-silent: a fork of whtsky/mypy-silent with support for suppressing multiple errors on a single line