2

使用mypy对python程序进行静态检查

 1 year ago
source link: https://www.lujun9972.win/blog/2018/03/12/%E4%BD%BF%E7%94%A8mypy%E5%AF%B9python%E7%A8%8B%E5%BA%8F%E8%BF%9B%E8%A1%8C%E9%9D%99%E6%80%81%E6%A3%80%E6%9F%A5/index.html
Go to the source link to view the article. You can view the picture content, updated content and better typesetting reading experience. If the link is broken, please click the button below to view the snapshot at that time.

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。

[[email protected] 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:

[[email protected] work]$ mypy /tmp/test.py 
[[email protected] 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

[[email protected] 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。

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:

[[email protected] 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

About Joyk


Aggregate valuable and interesting links.
Joyk means Joy of geeK