re-apply types from .pyi stub files to your codebase
!!! Note this project is no longer supported/maintained as of 2022 August 14th !!!
Re-apply type annotations from .pyi stubs to your codebase.
Usage: retype [OPTIONS] [SRC]...
Re-apply type annotations from .pyi stubs to your codebase.
-p, --pyi-dir DIRECTORY Where to find .pyi stubs. [default: types]
-t, --target-dir DIRECTORY Where to write annotated sources. [default:
-i, --incremental Allow for missing type annotations in both stubs
and the source.
-q, --quiet Don't emit warnings, just errors.
-a, --replace-any Allow replacing Any annotations.
--hg Post-process files to preserve implicit byte
--traceback Show a Python traceback on error.
--version Show the version and exit.
--help Show this message and exit.
When you run
retype, it goes through all files you passed as SRC, finds the
corresponding .pyi files in the
types/ directory, and re-applies typing annotations
from .pyi to the sources, using the Python 3 function and variable annotation syntax.
The resulting combined sources are saved in
You can also pass directories as sources, in which case
retype will look for .py files
in them recursively.
It's smart enough to do the following:
- reapply typing imports
- reapply function argument annotations
- reapply function return value annotations
- reapply method argument and return value annotations
- reapply function-level variable annotations
- reapply module-level name annotations
- reapply module-level type aliases
- reapply class-level field annotations
- reapply instance-level field annotations
- validate existing source annotations against the .pyi file
- validate source function signatures against the .pyi file
- read function signature type comments in .pyi files
- read variable type comments in .pyi files
- consider existing source type comments as annotations
- remove duplicate type comments from source when annotations are applied
- normalize remaining type comments in the source to annotations; this is done even if the corresponding .pyi file is missing
List of things to be done
- add a --backward option to output type comments instead of annotations
- handle if sys.version_info and sys.platform checks in stubs
- it's okay for a given .pyi file to be incomplete (gradual typing, baby!)
- it's okay for functions and classes to be out of order in .pyi files and the source
- it's an error for a function or class to be missing in the source
- it's an error for a function's signature to be incompatible between the .pyi file and the source
- it's an error for an annotation in the source to be incompatible with the .pyi file
- Line numbers in the annotated source will no longer match original source code; this is because re-application of types requires copying typing imports and alias definitions from the .pyi file.
- While formatting of the original source will be preserved, formatting of the applied annotations might differ from the formatting in .pyi files.
- The source where type annotations get re-applied cannot use the legacy
- Class attribute annotations in
__init__()methods are moved verbatim to the respective
__init__()method in the implementation. They are never translated into class-level attribute annotations, so if that method is missing, the translation will fail. Similarly, class-level attribute annotations are never applied to
- Forward references in .pyi files will only be properly resolved for type aliases and
type vars (by inserting them right before they're used in the source). Other forms of
forward references will not work in the source code due to out-of-order class and
function definitions. Modify your .pyi files to use strings.
retypewill not automatically discover failing forward references and stringify them.
- Local variable annotations present in the .pyi file are transferred to the body level
of the given function in the source. In other words, if the source defines a variable
within a loop or a conditional statement branch,
retypewill create an value-less variable annotation at the beginning of the function. Use a broad type and constrain types in relevant code paths using
- Because of the above, existing source variable annotations and type comments buried in
conditionals and loops will not be deduplicated (and
mypywill complain that a name was already defined).
- An async function in the stub will match a regular function of the same name in the
same scope and vice versa. This is to enable annotating async functions spelled with
OMG, this is Python 3 only!
Relax, you can run retype as a tool perfectly fine under Python 3.6+ even if you want to analyze Python 2 code. This way you'll be able to parse all of the new syntax supported on Python 3 but also effectively all the Python 2 syntax at the same time.
By making the code exclusively Python 3.6+, I'm able to focus on the quality of the checks and re-use all the nice features of the new releases (check out pathlib or f-strings) instead of wasting cycles on Unicode compatibility, etc.
Note: to retype modules using f-strings you need to run on Python 3.6.2+ due to bpo-23894.
- Mark python3.8 and python3.9 compatible
- add a module entry-point, now you can call it via
python -m retype
- automatically all files excluded by
.gitignoreon merge of folders
- support for
- fix a bug that meant the merge was not recursive in paths
setup.cfgbased packaging configuration
- add PEP-517/8 declaration via
- include license in both wheel and sdist
- this projects code base is now formatted with black, import ordered via isort, and uses Azure Pipelines instead of Travis (also testing on Windows and macOs)
support --replace-any to allow replacing pre-existing
Anyannotations without raising errors
bugfix: don't re-apply
# type: ignoreas an annotation if followed by another comment. Original patch by Shannon Zhu.
bugfix: don't try to re-apply
# type: ignoreas a function annotation
bugfix: support arbitrary source file encodings, patch by Michael Overmeyer.
bugfix: support missing newlines at the end of the file, patch by Michael Overmeyer.
bugfix: in --incremental, format default values according to PEP 8 (no spaces around the = sign if the type is missing)
- bugfix: --incremental didn't work with multiple arguments before
- support --incremental stub application (i.e. allow for both stubs and the source to be missing annotations for some arguments and/or return value)
support async functions
support --traceback for getting more information about internal errors
first published version
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