用Pylint规范化Python代码，附PyCharm配置

Pylint一个可以检查Python代码错误，执行代码规范的工具。它还可以对代码风格提出建议。

官网：https://pylint.readthedocs.io 

pip install pylint

默认情况，Pylint就已经随着Python安装好。在Python的scripts目录下。

找一段小程序试验一下Pylint，程序很简单。

#!/usr/bin/env python
# encoding: utf-8

'''
Created on 2017年2月4日

@author: Arthur Guo
'''

N = 10
YHTriangle = []
for i in range(N):  # 行
    YHTriangle.append([])
    if i == 0:
        YHTriangle[i].append(1) #第一行只有 1
    else:
        YHTriangle[i].append(1) #最左元素永远为 1
        YHTriangle[i].append(1) #最右元素永远为 1
        for j in range(1,i):    #中间元素
            if i <> 0 and i <> 1:
                YHTriangle[i].insert(j,YHTriangle[i-1][j-1] + YHTriangle[i-1][j])
for i in range(N):
    print YHTriangle[i]

命令行运行pylint yanghui.py，结果看起来很冗长

c:>c:Python27Scriptspylint.exe d:workspacePyCommsrcInterviewsyanghui.py

No config file found, using default configuration
************* Module Interviews.yanghui
C: 19, 0: Exactly one space required after comma
        for j in range(1,i):    #中间元素
                        ^ (bad-whitespace)
C: 21, 0: Exactly one space required after comma
                YHTriangle[i].insert(j,YHTriangle[i-1][j-1] + YHTriangle[i-1][j]
)
                                      ^ (bad-whitespace)
C: 23, 0: Final newline missing (missing-final-newline)
C: 11, 0: Invalid constant name "YHTriangle" (invalid-name)


Report
======
13 statements analysed.

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

+---------+-------+-----------+-----------+------------+---------+
|type     |number |old number |difference |%documented |%badname |
+=========+=======+===========+===========+============+=========+
|module   |1      |1          |=          |100.00      |0.00     |
+---------+-------+-----------+-----------+------------+---------+
|class    |0      |0          |=          |0           |0        |
+---------+-------+-----------+-----------+------------+---------+
|method   |0      |0          |=          |0           |0        |
+---------+-------+-----------+-----------+------------+---------+
|function |0      |0          |=          |0           |0        |
+---------+-------+-----------+-----------+------------+---------+



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

+----------+-------+------+---------+-----------+
|type      |number |%     |previous |difference |
+==========+=======+======+=========+===========+
|code      |15     |62.50 |15       |=          |
+----------+-------+------+---------+-----------+
|docstring |5      |20.83 |5        |=          |
+----------+-------+------+---------+-----------+
|comment   |2      |8.33  |17       |-15.00     |
+----------+-------+------+---------+-----------+
|empty     |2      |8.33  |3        |-1.00      |
+----------+-------+------+---------+-----------+



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

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



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

+-----------+-------+---------+-----------+
|type       |number |previous |difference |
+===========+=======+=========+===========+
|convention |4      |6        |-2.00      |
+-----------+-------+---------+-----------+
|refactor   |0      |0        |=          |
+-----------+-------+---------+-----------+
|warning    |0      |0        |=          |
+-----------+-------+---------+-----------+
|error      |0      |0        |=          |
+-----------+-------+---------+-----------+



Messages
--------

+----------------------+------------+
|message id            |occurrences |
+======================+============+
|bad-whitespace        |2           |
+----------------------+------------+
|missing-final-newline |1           |
+----------------------+------------+
|invalid-name          |1           |
+----------------------+------------+



Global evaluation
-----------------
Your code has been rated at 6.92/10 (previous run: 5.38/10, +1.54)

‘’‘’Report

=======‘’‘’以上是Pylint对程序的建议，以下都是报告内容。多数时候，我们其实并不想看那么冗长的报告。这时候，体贴的Pylint就让我们屏蔽掉它们。

加上参数 --reports=n 或者更简单写成 -rn 就好了。再看检查结果：

c:>c:Python27Scriptspylint.exe --reports=n d:workspacePyCommsrcInterview
syanghui.py
No config file found, using default configuration
************* Module Interviews.yanghui
C: 19, 0: Exactly one space required after comma
        for j in range(1,i):    #中间元素
                        ^ (bad-whitespace)
C: 21, 0: Exactly one space required after comma
                YHTriangle[i].insert(j,YHTriangle[i-1][j-1] + YHTriangle[i-1][j]
)
                                      ^ (bad-whitespace)
C: 23, 0: Final newline missing (missing-final-newline)
C: 11, 0: Invalid constant name "YHTriangle" (invalid-name)

建议分三种：“bad-whitespace”, "missing-final-newline", "invalid-name".

前两个好说，加空格，加空行。但是下面这个怎么破？

C: 11, 0: Invalid constant name "YHTriangle" (invalid-name)

命名不规范？认为是个constant值？ 其实可以把这类问题忽略掉。

“Invalid constant name” 错误号是 C0103，所以加上 --disable=C0103即可。

c:>c:Python27Scriptspylint.exe --reports=n --disable=c0103 d:workspacePyCo
mmsrcInterviewsyanghui.py
No config file found, using default configuration

没输出就是说名没问题了。

当然，还有更多的参数可以供选择。

=======================华丽丽的分割线===============================

平时写Python，我们几乎都不直接用命令行，而是用集成的IDE工具。比如猫哥常用的PyCharm。

Pylint官方文档提了可以支持PyCharm不过太简略了。

实际操作是这样的：

进入PyCharm，从菜单栏，依次进入： File -> Settings -> Tools -> External Tools。

“+”，进行添加。需要填写的部分分别是：“Name”，“Tool Settings -> Programs”、“Tool Settings -> Parameters”、“Tool Settings -> Working directory”。

注意：

“Parameters”里其它参数不管怎么写，必须在最后加上$FilePath$，“Working directory”里必须写 $FileDir。

另外，需要再添加“Output Filter”，在上图中间靠右。填写内容的“Regular expression to match output”，必须是：$FILE_PATH$:$LINE$: 最后那个是冒号。

配置完毕，选择一个Python程序，右键点击，快捷菜单中会有“Extensions Tools -> Pylint”，点击运行即可。输出结果在执行程序结果的窗口（IDE下半部分）。

如果看到返回值为0，说明程序没问题了。

C:Python27Scriptspylint.exe --reports=n --disable=C0103 D:PyCharmSpace	est1	est1hello.py
No config file found, using default configuration

Process finished with exit code 0