定制pattern的string模板(template) 详解

本文地址: http://blog.csdn.net/caroline_wendy/article/details/28625179

string.Template的pattern是一个正则表达式, 可以通过覆盖pattern属性, 定义新的正则表达式.

如: 使用新的定界符"{{", 把{{var}}作为变量语法.

代码:

# -*- coding: utf-8 -*-

‘‘‘

Created on 2014.6.5

@author: Administrator

@edition : python 3.3.0, eclipse pydev

‘‘‘

import string

t = string.Template(‘$var‘)

print(t.pattern.pattern)

class MyTemplate(string.Template):

delimiter = ‘{{‘

pattern = r‘‘‘

\{\{(?:

(?P\{\{) | # Escape sequence of two delimiters

(?P[_a-z][_a-z0-9]*)\}\} | # delimiter and a Python identifier

{(?P[_a-z][_a-z0-9]*)}\}\} | # delimiter and a braced identifier

(?P) # Other ill-formed delimiter exprs

)

‘‘‘

t2 = MyTemplate(‘‘‘

{{{{

{{var}}

‘‘‘)

print(‘MATCHES: ‘, t2.pattern.findall(t2.template))

print(‘SUBSTITUTED: ‘, t2.safe_substitute(var=‘replacement‘))

输出:

\$(?:

(?P\$) | # Escape sequence of two delimiters

(?P[_a-z][_a-z0-9]*) | # delimiter and a Python identifier

{(?P[_a-z][_a-z0-9]*)} | # delimiter and a braced identifier

(?P) # Other ill-formed delimiter exprs

)

MATCHES: [(‘{{‘, ‘‘, ‘‘, ‘‘), (‘‘, ‘var‘, ‘‘, ‘‘)]

SUBSTITUTED:

{{

replacement