Python代码分析工具：PyChecker、Pylint

时间：2014-05-13 03:06:30 阅读：922 评论：0 收藏：0 [点我收藏+]

标签：python 代码检查 pychecker pylint

1 概述

PyChecker是Python代码的静态分析工具，它能够帮助查找Python代码的bug，而且能够对代码的复杂度和格式等提出警告。

PyChecker可以工作在多种方式之下。首先，PyChecker会导入所检查文件中包含的模块，检查导入是否正确，同时检查文件中的函数、类和方法等。

PyChecker可以检查出来的问题有如下几种：

全局量没有找到，比如没有导入模块
传递给函数、方法、构造器的参数数目错误
传递给内建函数和方法的参数数目错误
字符串格式化信息不匹配
使用不存在的类方法和属性
覆盖函数时改变了签名
在同一作用域中重定义了函数、类、方法
使用未初始化的变量
方法的第一个参数不是self
未使用的全局量和本地量（模块或变量）
未使用的函数/方法的参数（不包括self）
模块、类、函数和方法中没有docstring

2 使用

从官网下载最新版本的PyChecker之后，解压安装即可：python setup.py install

首先可以在解压后的目录中测试一番：

[root@rango pychecker-0.8.19]# pychecker setup.py
Processing module setup (setup.py)...

Warnings...

[system path]/distutils/command/bdist_wininst.py:271: Statement appears to have no effect

[system path]/distutils/command/build_scripts.py:80: No class attribute (dry_run) found
[system path]/distutils/command/build_scripts.py:97: No class attribute (dry_run) found
[system path]/distutils/command/build_scripts.py:120: (file) shadows builtin
[system path]/distutils/command/build_scripts.py:121: No class attribute (dry_run) found

[system path]/distutils/command/install_data.py:62: (dir) shadows builtin
[system path]/distutils/command/install_data.py:64: (dir) shadows builtin
[system path]/distutils/command/install_data.py:66: (dir) shadows builtin

[system path]/distutils/command/install_scripts.py:52: (file) shadows builtin
[system path]/distutils/command/install_scripts.py:53: No class attribute (dry_run) found

19 errors suppressed, use -#/--limit to increase the number of errors displayed

可以看到，检查的结果将setup.py依赖的一些文件中的语法错误或者警告都列举出来了，使用--only参数可以只检查自身的语法问题：

[root@rango pychecker-0.8.19]# pychecker --only setup.py
Processing module setup (setup.py)...

Warnings...

None

参数和选项说明：pychecker [options] file1.py file2.py ...

--only 只给出命令行的文件的警告，默认为no

-#，--limit 显示的最大警告数，默认为10

--no-shadowbuiltin 检查是否有变量覆盖了内建变量，默认为off

-q，--stdlib 忽略标准库的文件的警告，默认为off

-T，--argsused 未使用的方法/函数的关键字，默认为on

修改默认配置和行为：.pycheckrc文件，该文件放置在$HOME目录下，--rcfile选项可以生成一份默认的配置文件。

要禁止一些模块/函数/类/方法的警告信息，可以在.pycheckrc文件中定义一个禁止字典，键类似：

‘module’，‘module.function’,‘module.class‘等。

或者直接在代码中定义：

__pychecker__ = ‘no-namedargs maxreturns=0 unsednames=foo,bar‘

其中__pychecker__格式的值和在禁止字典中的值是一样的

在代码文件中导入PyChecker模块及使用：

import pychecker.checker

这将会检查所有在PyChecker之后导入的模块，之前的不检查。

如果不能传递命令行参数，可以使用：

os.environ[‘PYCHECKER‘] = ‘command line options here‘

等价于在shell环境中设置PYCHECKER：

PYCHECKER=‘no-namedargs maxreturns=0‘ /path/to/your/program

要关闭警告，可以在导入PyChecker之前，加上：

os.environ[‘PYCHECKER_DISABLED‘] = 1

等价于在shell环境中设置PYCHECKER_DISABLED：

PYCHECKER_DISABLED=1 /path/to/your/program

3 Pylint

相比于PyChecker，Pylint是一个高阶的Python代码分析工具，它分析Python代码中的错误，查找不符合代码风格标准（Pylint 默认使用的代码风格是 PEP 8）和有潜在问题的代码。目前 Pylint 的最新版本是 pylint-1.2.1。可以检查一行代码的长度、变量名是否符合规范等。运行两次可以看出代码是否改进，分数是否有所提高，10分满分。

3.1 安装Pylint

从官网下载最新版本，解压之后，执行：python setup.py install，安装完毕

3.2 使用Pylint

命令行：pylint [options] module_or_package

图形化：pylint-gui

注解：pylint-gui依赖tkinter，安装tkinter：yum install -y tkinter

3.3 输出信息

Message_Type

(C) convention惯例。违反了编码风格标准
(R) refactor重构。写得非常糟糕的代码。
(W) warning警告。某些 Python 特定的问题。
(E) error错误。很可能是代码中的错误。
(F) 致命错误。阻止 Pylint 进一步运行的错误。

Report

report报告用来统计一些message类型的数量，模块的依赖等。检查module的数量,每个module错误和警告所占百分比

Global evaluation

代码评分

Global evaluation
-----------------
Your code has been rated at 7.98/10

示例：检查pylint-1.2.1目录下的setup.py文件：pylint setup.py

No config file found, using default configuration
************* Module pylint-1.2.1.setup
I: 3, 0: Locally disabling reimported (W0404) (locally-disabled)
I: 3, 0: Locally disabling redefined-builtin (W0622) (locally-disabled)
I: 3, 0: Locally disabling pointless-except (W0704) (locally-disabled)
I: 3, 0: Locally disabling unused-argument (W0613) (locally-disabled)
I: 42, 0: Locally disabling no-name-in-module (E0611) (locally-disabled)
C: 11, 0: Line too long (81/80) (line-too-long)
C:179, 0: Wrong hanging indentation.
‘pylint = pylint:run_pylint‘,
| ^ (bad-continuation)
C:180, 0: Wrong hanging indentation.
‘pylint-gui = pylint:run_pylint_gui‘,
| ^ (bad-continuation)
C:181, 0: Wrong hanging indentation.
‘epylint = pylint:run_epylint‘,
| ^ (bad-continuation)
C:182, 0: Wrong hanging indentation.
‘pyreverse = pylint:run_pyreverse‘,
| ^ (bad-continuation)
C:183, 0: Wrong hanging indentation.
‘symilar = pylint:run_symilar‘,
| ^ (bad-continuation)
C:184, 0: Wrong hanging indentation.
]}
| | ^ (bad-continuation)
C:199, 0: Wrong continued indentation.
‘build_py‘: build_py},
| ^ (bad-continuation)
C:202, 0: No space allowed before :
if __name__ == ‘__main__‘ :
^ (bad-whitespace)
F: 54, 0: Unable to import ‘__pkginfo__‘ (import-error)
C: 57, 0: Invalid constant name "distname" (invalid-name)
C: 58, 0: Invalid constant name "scripts" (invalid-name)
C: 59, 0: Invalid constant name "data_files" (invalid-name)
C: 60, 0: Invalid constant name "subpackage_of" (invalid-name)
C: 61, 0: Invalid constant name "include_dirs" (invalid-name)
C: 62, 0: Invalid constant name "ext_modules" (invalid-name)
C: 63, 0: Invalid constant name "install_requires" (invalid-name)
C: 64, 0: Invalid constant name "dependency_links" (invalid-name)
C: 71, 4: Invalid constant name "long_description" (invalid-name)
C: 73, 4: Invalid constant name "long_description" (invalid-name)
C:139,24: Invalid variable name "n" (invalid-name)
W:138,30: Unused variable ‘dirnames‘ (unused-variable)
R:105, 0: Too many public methods (32/20) (too-many-public-methods)

Report
======
109 statements analysed.

Statistics by type
------------------

+---------+-------+-----------+-----------+------------+---------+
|type |number |old number |difference |%documented |%badname |
+=========+=======+===========+===========+============+=========+
|module |1 |1 |= |100.00 |0.00 |
+---------+-------+-----------+-----------+------------+---------+
|class |1 |1 |= |100.00 |0.00 |
+---------+-------+-----------+-----------+------------+---------+
|method |2 |2 |= |100.00 |0.00 |
+---------+-------+-----------+-----------+------------+---------+
|function |3 |3 |= |100.00 |0.00 |
+---------+-------+-----------+-----------+------------+---------+

Duplication
-----------

+-------------------------+------+---------+-----------+
| |now |previous |difference |
+=========================+======+=========+===========+
|nb duplicated lines |0 |0 |= |
+-------------------------+------+---------+-----------+
|percent duplicated lines |0.000 |0.000 |= |
+-------------------------+------+---------+-----------+

Messages by category
--------------------

+-----------+-------+---------+-----------+
|type |number |previous |difference |
+===========+=======+=========+===========+
|convention |20 |20 |= |
+-----------+-------+---------+-----------+
|refactor |1 |1 |= |
+-----------+-------+---------+-----------+
|warning |1 |1 |= |
+-----------+-------+---------+-----------+
|error |0 |0 |= |
+-----------+-------+---------+-----------+

Messages
--------

+------------------------+------------+
|message id |occurrences |
+========================+============+
|invalid-name |11 |
+------------------------+------------+
|bad-continuation |7 |
+------------------------+------------+
|locally-disabled |5 |
+------------------------+------------+
|unused-variable |1 |
+------------------------+------------+
|too-many-public-methods |1 |
+------------------------+------------+
|line-too-long |1 |
+------------------------+------------+
|import-error |1 |
+------------------------+------------+
|bad-whitespace |1 |
+------------------------+------------+

Global evaluation
-----------------
Your code has been rated at 7.98/10 (previous run: 7.98/10, +0.00)

Raw metrics
-----------

+----------+-------+------+---------+-----------+
|type |number |% |previous |difference |
+==========+=======+======+=========+===========+
|code |133 |68.56 |133 |= |
+----------+-------+------+---------+-----------+
|docstring |18 |9.28 |18 |= |
+----------+-------+------+---------+-----------+
|comment |28 |14.43 |28 |= |
+----------+-------+------+---------+-----------+
|empty |15 |7.73 |15 |= |
+----------+-------+------+---------+-----------+

External dependencies
---------------------
::

setuptools (pylint-1.2.1.setup)
\-command
\-install_lib (pylint-1.2.1.setup)

3.4 常用命令行参数和选项

-h,--help

显示所有帮助信息。

--generate-rcfile

可以使用 pylint --generate-rcfile 来生成一个配置文件示例。可以使用重定向把这个配置文件保存下来用做以后使用。也可以在前面加上其它选项，使这些选项的值被包含在这个产生的配置文件里。如：pylint --persistent=n --generate-rcfile > pylint.conf，查看 pylint.conf，可以看到 persistent=no，而不再是其默认值 yes。