Python 2.6+ str.format() and regular expressions

Question

Using str.format() is the new standard for formatting strings in Python 2.6, and Python 3. I\'ve run into an issue when using str.format() with reg

Answer 1

Per the documentation, if you need a literal { or } to survive the formatting opertation, use {{ and }} in the original string.

'^(w{{3}}\.)?([0-9A-Za-z-]+\.){{1}}{domainName}$'.format(domainName = 'delivery.com')

Answer 2

you first would need to format string and then use regex. It really doesn't worth it to put everything into a single line. Escaping is done by doubling the curly braces:

>>> pat= '^(w{{3}}\.)?([0-9A-Za-z-]+\.){{1}}{domainName}$'.format(domainName = 'delivery.com')
>>> pat
'^(w{3}\\.)?([0-9A-Za-z-]+\\.){1}delivery.com$'
>>> re.match(pat, str1)

Also, re.match is matching at the beginning of the string, you don't have to put ^ if you use re.match, you need ^ if you're using re.search, however.

Please note, that {1} in regex is rather redundant.