使用mypy对python程序进行静态检查
自从python3.6开始，允许为参数和返回类型添加 type hint，这使得对python程序进行静态检查成为可能。
mypy就是这么一个python type checker.
安装mypy
我们可以使用 pip 来安装mypy。
[lujun9972@T520 work]$ pip install mypy
Collecting mypy
Downloading mypy-0.570-py3-none-any.whl (1.2MB)
100% |████████████████████████████████| 1.2MB 70kB/s
Collecting typed-ast<1.2.0,>=1.1.0 (from mypy)
Downloading typed_ast-1.1.0-cp36-cp36m-manylinux1_x86_64.whl (724kB)
100% |████████████████████████████████| 727kB 68kB/s
Installing collected packages: typed-ast, mypy
Successfully installed mypy-0.570 typed-ast-1.1.0
使用mypy进行静态检查
假设有这么一个 test.py 的文件：
class Student(): def __init__(self,id,name,age,major): self.id = id self.name = name self.age = age self.major = major def display(persons): for person in persons: print(f'{person.id} {person.name}') dark = Student('1', 'Dark', '19', 'computer') sun = Student('2', 'Sun', 21, 'account') lujun= Student(3, 'lujun', 'MBA', 25) display(dark) display([sun, dark, 'lujun'])
这段代码并没有添加 type hint，但是从代码中可以很容易看出是有许多错误的。
我们用 mypy 来检查一下看能不能查出什么：
[lujun9972@T520 work]$ mypy /tmp/test.py [lujun9972@T520 work]$
你会发现 mypy 什么错误都没有提示。
现在我们来为程序加上type hint
from typing import List class Student(): def __init__(self, id:int, name:str, age:int, major:str)->None: self.id = id self.name = name self.age = age self.major = major def display(persons:List[Student])->None: for person in persons: print(f'{person.id} {person.name}') dark = Student('1', 'Dark', '19', 'computer') sun = Student('2', 'Sun', 21, 'account') lujun= Student(3, 'lujun', 'MBA', 25) display(dark) display([sun, dark, 'lujun'])
再次用 mypy 来检查一下
[lujun9972@T520 work]$ mypy /tmp/test_with_type_hint.py /tmp/test_with_type_hint.py:14: error: Argument 1 to "Student" has incompatible type "str"; expected "int" /tmp/test_with_type_hint.py:14: error: Argument 3 to "Student" has incompatible type "str"; expected "int" /tmp/test_with_type_hint.py:15: error: Argument 1 to "Student" has incompatible type "str"; expected "int" /tmp/test_with_type_hint.py:16: error: Argument 3 to "Student" has incompatible type "str"; expected "int" /tmp/test_with_type_hint.py:16: error: Argument 4 to "Student" has incompatible type "int"; expected "str" /tmp/test_with_type_hint.py:18: error: Argument 1 to "display" has incompatible type "Student"; expected "List[Student]" /tmp/test_with_type_hint.py:19: error: List item 2 has incompatible type "str"; expected "Student"
可以发现，找出了一堆问题。
帮助信息
mypy还带有一堆的参数来定义检查的方法，运行 mypy -h 就会列出帮助信息了：
[lujun9972@T520 work]$ mypy --help
usage: mypy [-h] [-v] [-V] [--python-version x.y] [--platform PLATFORM] [-2]
[--ignore-missing-imports]
[--follow-imports {normal,silent,skip,error}]
[--disallow-any-unimported] [--disallow-any-expr]
[--disallow-any-decorated] [--disallow-any-explicit]
[--disallow-any-generics] [--disallow-untyped-calls]
[--disallow-untyped-defs] [--disallow-incomplete-defs]
[--check-untyped-defs] [--disallow-subclassing-any]
[--warn-incomplete-stub] [--disallow-untyped-decorators]
[--warn-redundant-casts] [--no-warn-no-return] [--warn-return-any]
[--warn-unused-ignores] [--warn-unused-configs]
[--show-error-context] [--no-implicit-optional] [-i]
[--quick-and-dirty] [--cache-dir DIR] [--cache-fine-grained]
[--skip-version-check] [--strict-optional]
[--strict-optional-whitelist [GLOB [GLOB ...]]]
[--junit-xml JUNIT_XML] [--pdb] [--show-traceback] [--stats]
[--inferstats] [--custom-typing MODULE]
[--custom-typeshed-dir DIR] [--scripts-are-modules]
[--config-file CONFIG_FILE] [--show-column-numbers]
[--find-occurrences CLASS.MEMBER] [--strict]
[--shadow-file SOURCE_FILE SHADOW_FILE] [--any-exprs-report DIR]
[--cobertura-xml-report DIR] [--html-report DIR]
[--linecount-report DIR] [--linecoverage-report DIR]
[--memory-xml-report DIR] [--txt-report DIR] [--xml-report DIR]
[--xslt-html-report DIR] [--xslt-txt-report DIR] [-m MODULE]
[-c PROGRAM_TEXT] [-p PACKAGE]
[files [files ...]]
optional arguments:
-h, --help show this help message and exit
-v, --verbose more verbose messages
-V, --version show program's version number and exit
--python-version x.y use Python x.y
--platform PLATFORM typecheck special-cased code for the given OS
platform (defaults to sys.platform).
-2, --py2 use Python 2 mode
--ignore-missing-imports silently ignore imports of missing modules
--follow-imports {normal,silent,skip,error}
how to treat imports (default normal)
--disallow-any-unimported
disallow Any types resulting from unfollowed
imports
--disallow-any-expr disallow all expressions that have type Any
--disallow-any-decorated disallow functions that have Any in their
signature after decorator transformation
--disallow-any-explicit disallow explicit Any in type positions
--disallow-any-generics disallow usage of generic types that do not
specify explicit type parameters
--disallow-untyped-calls disallow calling functions without type
annotations from functions with type annotations
(inverse: --allow-untyped-calls)
--disallow-untyped-defs disallow defining functions without type
annotations or with incomplete type annotations
(inverse: --allow-untyped-defs)
--disallow-incomplete-defs
disallow defining functions with incomplete type
annotations (inverse: --allow-incomplete-defs)
--check-untyped-defs type check the interior of functions without type
annotations (inverse: --no-check-untyped-defs)
--disallow-subclassing-any
disallow subclassing values of type 'Any' when
defining classes (inverse: --allow-subclassing-
any)
--warn-incomplete-stub warn if missing type annotation in typeshed, only
relevant with --check-untyped-defs enabled
(inverse: --no-warn-incomplete-stub)
--disallow-untyped-decorators
disallow decorating typed functions with untyped
decorators (inverse: --allow-untyped-decorators)
--warn-redundant-casts warn about casting an expression to its inferred
type (inverse: --no-warn-redundant-casts)
--no-warn-no-return do not warn about functions that end without
returning (inverse: --warn-no-return)
--warn-return-any warn about returning values of type Any from non-
Any typed functions (inverse: --no-warn-return-
any)
--warn-unused-ignores warn about unneeded '# type: ignore' comments
(inverse: --no-warn-unused-ignores)
--warn-unused-configs warn about unused '[mypy-<pattern>]' config
sections (inverse: --no-warn-unused-configs)
--show-error-context Precede errors with "note:" messages explaining
context (inverse: --hide-error-context)
--no-implicit-optional don't assume arguments with default values of None
are Optional (inverse: --implicit-optional)
-i, --incremental enable module cache, (inverse: --no-incremental)
--quick-and-dirty use cache even if dependencies out of date
(implies --incremental)
--cache-dir DIR store module cache info in the given folder in
incremental mode (defaults to '.mypy_cache')
--cache-fine-grained include fine-grained dependency information in the
cache
--skip-version-check allow using cache written by older mypy version
--strict-optional enable experimental strict Optional checks
(inverse: --no-strict-optional)
--strict-optional-whitelist [GLOB [GLOB ...]]
suppress strict Optional errors in all but the
provided files (experimental -- read documentation
before using!). Implies --strict-optional. Has the
undesirable side-effect of suppressing other
errors in non-whitelisted files.
--junit-xml JUNIT_XML write junit.xml to the given file
--pdb invoke pdb on fatal error
--show-traceback, --tb show traceback on fatal error
--stats dump stats
--inferstats dump type inference stats
--custom-typing MODULE use a custom typing module
--custom-typeshed-dir DIR
use the custom typeshed in DIR
--scripts-are-modules Script x becomes module x instead of __main__
--config-file CONFIG_FILE
Configuration file, must have a [mypy] section
(defaults to mypy.ini)
--show-column-numbers Show column numbers in error messages (inverse:
--hide-column-numbers)
--find-occurrences CLASS.MEMBER
print out all usages of a class member
(experimental)
--strict Strict mode. Enables the following flags:
--disallow-untyped-calls, --disallow-untyped-defs,
--disallow-incomplete-defs, --check-untyped-defs,
--disallow-subclassing-any, --disallow-untyped-
decorators, --warn-redundant-casts, --warn-return-
any, --warn-unused-ignores, --warn-unused-configs,
--no-implicit-optional, --strict-optional
--shadow-file SOURCE_FILE SHADOW_FILE
Typecheck SHADOW_FILE in place of SOURCE_FILE.
report generation:
Generate a report in the specified format.
--any-exprs-report DIR
--cobertura-xml-report DIR
--html-report DIR
--linecount-report DIR
--linecoverage-report DIR
--memory-xml-report DIR
--txt-report DIR
--xml-report DIR
--xslt-html-report DIR
--xslt-txt-report DIR
How to specify the code to type check:
-m MODULE, --module MODULE
type-check module; can repeat for more modules
-c PROGRAM_TEXT, --command PROGRAM_TEXT
type-check program passed in as string
-p PACKAGE, --package PACKAGE
type-check all files in a directory
files type-check given files or directories
environment variables: MYPYPATH additional module search path
