Customize pattern’s string templates (template) for details

pattern of string.Template is a regular expression that can be defined by overwriting the pattern property.

For example, use the new delimiter ”{{” and use {{var}} as the variable syntax.

Code:

# -*- 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'))

Output:

  \$(?:
   (?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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