Python - 定制pattern的string模板(template) 具体解释

定制pattern的string模板(template) 具体解释

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

string.Template的pattern是一个正則表達式, 能够通过覆盖pattern属性, 定义新的正則表達式.

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