Python - 定制pattern的string模板(template) 详解

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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 stringt = string.Template('$var')print(t.pattern.pattern)class MyTemplate(string.Template):    delimiter = '{{'    pattern = r'''    \{\{(?:      (?P<escaped>\{\{) |   # Escape sequence of two delimiters      (?P<named>[_a-z][_a-z0-9]*)\}\}      |   # delimiter and a Python identifier      {(?P<braced>[_a-z][_a-z0-9]*)}\}\}   |   # delimiter and a braced identifier      (?P<invalid>)              # 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<escaped>\$) |   # Escape sequence of two delimiters      (?P<named>[_a-z][_a-z0-9]*)      |   # delimiter and a Python identifier      {(?P<braced>[_a-z][_a-z0-9]*)}   |   # delimiter and a braced identifier      (?P<invalid>)              # Other ill-formed delimiter exprs    )    MATCHES:  [('{{', '', '', ''), ('', 'var', '', '')]SUBSTITUTED:  {{replacement

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