# -*- coding: utf-8 -*- 

import string 
 
template_text = ''''' 
  Delimiter : %% 
  Replaced : %with_underscore 
  Ingored : %notunderscored 
''' 
 
d = {'with_underscore' : 'replaced', 
   'notunderscored' : 'not replaced'} 
 
class MyTemplate(string.Template): 
  delimiter = '%' 
  idpattern = '[a-z]+_[a-z]+' 
   
t = MyTemplate(template_text) 
print('Modified ID pattern: ') 
print(t.safe_substitute(d)) 

Modified ID pattern:  
 
  Delimiter : % 
  Replaced : replaced 
  Ingored : %notunderscored 

import string 
 
t = string.Template('$var') 
print(t.pattern.pattern) 
 
class MyTemplate(string.Template): 
  delimiter = '{{' 
  pattern = r''''' 
  \{\{("htmlcode">

  \$("htmlcode">

import string 
 
values = {'var' : 'foo'} 
 
t = string.Template('''''$var is here but $ missing is not provided! ''') 
 
 
try: 
  print 'substitute() : ', t.substitute(values) 
except ValueError as err: 
  print 'Error:', str(err) 
   
print 'safe_substitude() : ', t.safe_substitute(values) 



输出:


substitute() : Error: Invalid placeholder in string: line 1, col 18 
safe_substitude() : foo is here but $ missing is not provided!