字符串模板的安全替换(safe_substitute) 具体解释

本文地址: http://blog.csdn.net/caroline_wendy/article/details/27057339

字符串模板(sting.Template), 替换时, 使用substitute(), 未能提供模板所需的所有參数值时, 会发生异常.

假设使用safe_substitute(), 即安全替换, 则会替换存在的字典值, 保留未存在的替换符号.

代码:

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

‘‘‘
Created on 2014.5.26

@author: C.L.Wang

Eclipse Pydev python 2.7.5
‘‘‘

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)

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