Mypy supports reading configuration settings from a file. By default it uses the file mypy.ini
with a fallback to .mypy.ini
, then setup.cfg
in the current directory, then $XDG_CONFIG_HOME/mypy/config
, then ~/.config/mypy/config
, and finally .mypy.ini
in the user home directory if none of them are found; the --config-file <mypy --config-file>
command-line flag can be used to read a different file instead (see config-file-flag
).
It is important to understand that there is no merging of configuration files, as it would lead to ambiguity. The --config-file <mypy --config-file>
flag has the highest precedence and must be correct; otherwise mypy will report an error and exit. Without command line option, mypy will look for defaults, but will use only one of them. The first one to read is mypy.ini
, then .mypy.ini
, and finally setup.cfg
.
Most flags correspond closely to command-line flags
<command-line>
but there are some differences in flag names and some flags may take a different value based on the module being processed.
Some flags support user home directory and environment variable expansion. To refer to the user home directory, use ~
at the beginning of the path. To expand environment variables use $VARNAME
or ${VARNAME}
.
The configuration file format is the usual ini file <python:library/configparser>
format. It should contain section names in square brackets and flag settings of the form NAME = VALUE. Comments start with #
characters.
- A section named
[mypy]
must be present. This specifies the global flags. Thesetup.cfg
file is an exception to this. Additional sections named
[mypy-PATTERN1,PATTERN2,...]
may be present, wherePATTERN1
,PATTERN2
, etc., are comma-separated patterns of fully-qualified module names, with some components optionally replaced by the '' character (e.g. ``foo.bar``, ``foo.bar.,
foo..baz``). These sections specify additional flags that only apply tomodules* whose name matches at least one of the patterns.A pattern of the form
qualified_module_name
matches only the named module, whiledotted_module_name.*
matchesdotted_module_name
and any submodules (sofoo.bar.*
would match all offoo.bar
,foo.bar.baz
, andfoo.bar.baz.quux
).Patterns may also be "unstructured" wildcards, in which stars may appear in the middle of a name (e.g
site.*.migrations.*
). Stars match zero or more module components (sosite.*.migrations.*
can matchsite.migrations
).- When options conflict, the precedence order for configuration is:
Inline configuration <inline-config>
in the source file- Sections with concrete module names (
foo.bar
) - Sections with "unstructured" wildcard patterns (
foo.*.baz
), with sections later in the configuration file overriding sections earlier. - Sections with "well-structured" wildcard patterns (
foo.bar.*
), with more specific overriding more general. - Command line options.
- Top-level configuration file options.
The difference in precedence order between "structured" patterns (by specificity) and "unstructured" patterns (by order in the file) is unfortunate, and is subject to change in future versions.
Note
The warn_unused_configs
flag may be useful to debug misspelled section names.
Note
Configuration flags are liable to change between releases.
Some of the config options may be set either globally (in the [mypy]
section) or on a per-module basis (in sections like [mypy-foo.bar]
).
If you set an option both globally and for a specific module, the module configuration options take precedence. This lets you set global defaults and override them on a module-by-module basis. If multiple pattern sections match a module, the options from the
most specific section are used where they disagree <config-precedence>
.
Some other options, as specified in their description, may only be set in the global section ([mypy]
).
Options that take a boolean value may be inverted by adding no_
to their name or by (when applicable) swapping their prefix from disallow
to allow
(and vice versa).
Here is an example of a mypy.ini
file. To use this config file, place it at the root of your repo and run mypy.
# Global options:
[mypy]
python_version = 2.7
warn_return_any = True
warn_unused_configs = True
# Per-module options:
[mypy-mycode.foo.*]
disallow_untyped_defs = True
[mypy-mycode.bar]
warn_return_any = False
[mypy-somelibrary]
ignore_missing_imports = True
This config file specifies three global options in the [mypy]
section. These three options will:
- Type-check your entire project assuming it will be run using Python 2.7. (This is equivalent to using the
--python-version 2.7 <mypy --python-version>
or-2 <mypy -2>
flag). - Report an error whenever a function returns a value that is inferred to have type
Any
. - Report any config options that are unused by mypy. (This will help us catch typos when making changes to our config file).
Next, this module specifies three per-module options. The first two options change how mypy type checks code in mycode.foo.*
and mycode.bar
, which we assume here are two modules that you wrote. The final config option changes how mypy type checks somelibrary
, which we assume here is some 3rd party library you've installed and are importing. These options will:
- Selectively disallow untyped function definitions only within the
mycode.foo
package -- that is, only for function definitions defined in themycode/foo
directory. - Selectively disable the "function is returning any" warnings within
mycode.bar
only. This overrides the global default we set earlier. - Suppress any error messages generated when your codebase tries importing the module
somelibrary
. This is useful ifsomelibrary
is some 3rd party library missing type hints.
For more information, see the Import discovery <import-discovery>
section of the command line docs.
mypy_path
(string)Specifies the paths to use, after trying the paths from
MYPYPATH
environment variable. Useful if you'd like to keep stubs in your repo, along with the config file. Multiple paths are always separated with a:
or,
regardless of the platform. User home directory and environment variables will be expanded.This option may only be set in the global section (
[mypy]
).Note: On Windows, use UNC paths to avoid using
:
(e.g.\\127.0.0.1\X$\MyDir
whereX
is the drive letter).files
(comma-separated list of strings)A comma-separated list of paths which should be checked by mypy if none are given on the command line. Supports recursive file globbing using :py
glob
, where*
(e.g.*.py
) matches files in the current directory and**/
(e.g.**/*.py
) matches files in any directories below the current one. User home directory and environment variables will be expanded.This option may only be set in the global section (
[mypy]
).namespace_packages
(bool, default False)Enables
420
style namespace packages. Seethe corresponding flag <import-discovery>
for more information.This option may only be set in the global section (
[mypy]
).ignore_missing_imports
(bool, default False)Suppresses error messages about imports that cannot be resolved.
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.
follow_imports
(string, defaultnormal
)Directs what to do with imports when the imported module is found as a
.py
file and not part of the files, modules and packages provided on the command line.The four possible values are
normal
,silent
,skip
anderror
. For explanations see the discussion for the--follow-imports <follow-imports>
command line flag.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.
follow_imports_for_stubs
(bool, default False)Determines whether to respect the
follow_imports
setting even for stub (.pyi
) files.Used in conjunction with
follow_imports=skip
, this can be used to suppress the import of a module fromtypeshed
, replacing it withAny
.Used in conjunction with
follow_imports=error
, this can be used to make any use of a particulartypeshed
module an error.python_executable
(string)Specifies the path to the Python executable to inspect to collect a list of available
PEP 561 packages <installed-packages>
. User home directory and environment variables will be expanded. Defaults to the executable used to run mypy.This option may only be set in the global section (
[mypy]
).no_site_packages
(bool, default False)Disables using type information in installed packages (see
561
). This will also disable searching for a usable Python executable. This acts the same as--no-site-packages <mypy --no-site-packages>
command line flag.no_silence_site_packages
(bool, default False)Enables reporting error messages generated within installed packages (see
561
for more details on distributing type information). Those error messages are suppressed by default, since you are usually not able to control errors in 3rd party code.This option may only be set in the global section (
[mypy]
).
python_version
(string)Specifies the Python version used to parse and check the target program. The string should be in the format
DIGIT.DIGIT
--for example2.7
. The default is the version of the Python interpreter used to run mypy.This option may only be set in the global section (
[mypy]
).platform
(string)Specifies the OS platform for the target program, for example
darwin
orwin32
(meaning OS X or Windows, respectively). The default is the current platform as revealed by Python's :pysys.platform
variable.This option may only be set in the global section (
[mypy]
).always_true
(comma-separated list of strings)Specifies a list of variables that mypy will treat as compile-time constants that are always true.
always_false
(comma-separated list of strings)Specifies a list of variables that mypy will treat as compile-time constants that are always false.
For more information, see the Disallow dynamic typing <disallow-dynamic-typing>
section of the command line docs.
disallow_any_unimported
(bool, default False)Disallows usage of types that come from unfollowed imports (anything imported from an unfollowed import is automatically given a type of
Any
).disallow_any_expr
(bool, default False)Disallows all expressions in the module that have type
Any
.disallow_any_decorated
(bool, default False)Disallows functions that have
Any
in their signature after decorator transformation.disallow_any_explicit
(bool, default False)Disallows explicit
Any
in type positions such as type annotations and generic type parameters.disallow_any_generics
(bool, default False)Disallows usage of generic types that do not specify explicit type parameters.
disallow_subclassing_any
(bool, default False)Disallows subclassing a value of type
Any
.
For more information, see the Untyped definitions and calls <untyped-definitions-and-calls>
section of the command line docs.
disallow_untyped_calls
(bool, default False)Disallows calling functions without type annotations from functions with type annotations.
disallow_untyped_defs
(bool, default False)Disallows defining functions without type annotations or with incomplete type annotations.
disallow_incomplete_defs
(bool, default False)Disallows defining functions with incomplete type annotations.
check_untyped_defs
(bool, default False)Type-checks the interior of functions without type annotations.
disallow_untyped_decorators
(bool, default False)Reports an error whenever a function with type annotations is decorated with a decorator without annotations.
For more information, see the None and Optional handling <none-and-optional-handling>
section of the command line docs.
no_implicit_optional
(bool, default False)Changes the treatment of arguments with a default value of
None
by not implicitly making their type :py~typing.Optional
.strict_optional
(bool, default True)Enables or disables strict Optional checks. If False, mypy treats
None
as compatible with every type.Note: This was False by default in mypy versions earlier than 0.600.
For more information, see the Configuring warnings <configuring-warnings>
section of the command line docs.
warn_redundant_casts
(bool, default False)Warns about casting an expression to its inferred type.
This option may only be set in the global section (
[mypy]
).warn_unused_ignores
(bool, default False)Warns about unneeded
# type: ignore
comments.warn_no_return
(bool, default True)Shows errors for missing return statements on some execution paths.
warn_return_any
(bool, default False)Shows a warning when returning a value with type
Any
from a function declared with a non-Any
return type.warn_unreachable
(bool, default False)Shows a warning when encountering any code inferred to be unreachable or redundant after performing type analysis.
Note: these configuration options are available in the config file only. There is no analog available via the command line options.
show_none_errors
(bool, default True)Shows errors related to strict
None
checking, if the globalstrict_optional
flag is enabled.ignore_errors
(bool, default False)Ignores all non-fatal errors.
allow_untyped_globals
(bool, default False)Causes mypy to suppress errors caused by not being able to fully infer the types of global and class variables.
allow_redefinition
(bool, default False)Allows variables to be redefined with an arbitrary type, as long as the redefinition is in the same block and nesting level as the original definition.
implicit_reexport
(bool, default True)By default, imported values to a module are treated as exported and mypy allows other modules to import them. When false, mypy will not re-export unless the item is imported using from-as or is included in
__all__
. Note that mypy treats stub files as if this is always disabled. For example:# This won't re-export the value from foo import bar # This will re-export it as bar and allow other modules to import it from foo import bar as bar # This will also re-export bar from foo import bar __all__ = ['bar']
strict_equality
(bool, default False)Prohibit equality checks, identity checks, and container checks between non-overlapping types.
For more information, see the Configuring error messages <configuring-error-messages>
section of the command line docs.
These options may only be set in the global section ([mypy]
).
show_error_context
(bool, default False)Prefixes each error with the relevant context.
show_column_numbers
(bool, default False)Shows column numbers in error messages.
show_error_codes
(bool, default False)Shows error codes in error messages. See
error-codes
for more information.pretty
(bool, default False)Use visually nicer output in error messages: use soft word wrap, show source code snippets, and show error location markers.
color_output
(bool, default True)Shows error messages with color enabled.
error_summary
(bool, default True)Shows a short summary line after error messages.
show_absolute_path
(bool, default False)Show absolute paths to files.
These options may only be set in the global section ([mypy]
).
incremental
(bool, default True)Enables
incremental mode <incremental>
.cache_dir
(string, default.mypy_cache
)Specifies the location where mypy stores incremental cache info. User home directory and environment variables will be expanded. This setting will be overridden by the
MYPY_CACHE_DIR
environment variable.Note that the cache is only read when incremental mode is enabled but is always written to, unless the value is set to
/dev/null
(UNIX) ornul
(Windows).sqlite_cache
(bool, default False)Use an SQLite database to store the cache.
cache_fine_grained
(bool, default False)Include fine-grained dependency information in the cache for the mypy daemon.
skip_version_check
(bool, default False)Makes mypy use incremental cache data even if it was generated by a different version of mypy. (By default, mypy will perform a version check and regenerate the cache if it was written by older versions of mypy.)
skip_cache_mtime_checks
(bool, default False)Skip cache internal consistency checks based on mtime.
These options may only be set in the global section ([mypy]
).
pdb
(bool, default False)Invokes pdb on fatal error.
show_traceback
(bool, default False)Shows traceback on fatal error.
raise_exceptions
(bool, default False)Raise exception on fatal error.
custom_typing_module
(string)Specifies a custom module to use as a substitute for the :py
typing
module.custom_typeshed_dir
(string)Specifies an alternative directory to look for stubs instead of the default
typeshed
directory. User home directory and environment variables will be expanded.warn_incomplete_stub
(bool, default False)Warns about missing type annotations in typeshed. This is only relevant in combination with
disallow_untyped_defs
ordisallow_incomplete_defs
.
If these options are set, mypy will generate a report in the specified format into the specified directory.
any_exprs_report
(string)Causes mypy to generate a text file report documenting how many expressions of type
Any
are present within your codebase.cobertura_xml_report
(string)Causes mypy to generate a Cobertura XML type checking coverage report.
You must install the lxml library to generate this report.
html_report
/xslt_html_report
(string)Causes mypy to generate an HTML type checking coverage report.
You must install the lxml library to generate this report.
linecount_report
(string)Causes mypy to generate a text file report documenting the functions and lines that are typed and untyped within your codebase.
linecoverage_report
(string)Causes mypy to generate a JSON file that maps each source file's absolute filename to a list of line numbers that belong to typed functions in that file.
lineprecision_report
(string)Causes mypy to generate a flat text file report with per-module statistics of how many lines are typechecked etc.
txt_report
/xslt_txt_report
(string)Causes mypy to generate a text file type checking coverage report.
You must install the lxml library to generate this report.
xml_report
(string)Causes mypy to generate an XML type checking coverage report.
You must install the lxml library to generate this report.
These options may only be set in the global section ([mypy]
).
junit_xml
(string)Causes mypy to generate a JUnit XML test result document with type checking results. This can make it easier to integrate mypy with continuous integration (CI) tools.
scripts_are_modules
(bool, default False)Makes script
x
become modulex
instead of__main__
. This is useful when checking multiple scripts in a single run.warn_unused_configs
(bool, default False)Warns about per-module sections in the config file that do not match any files processed when invoking mypy. (This requires turning off incremental mode using
incremental = False
.)verbosity
(integer, default 0)Controls how much debug output will be generated. Higher numbers are more verbose.