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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