定制pattern的string模板(template) 详解

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<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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