Python 中开发pattern的string模板(template) 实例详解

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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