Tal Einat wrote:
Erick Tryzelaar wrote:
I find that when I'm normalizing strings, I end up writing this a lot:
sites = ['www.google.com', 'http://python.org', 'www.yahoo.com'] new_sites =  for site in sites: if site.startswith('http://'): site = site[len('http://'):] new_sites.append(site)
But it'd be much nicer if I could use a convenience function trim that would do this for me, so I could just use a comprehension:
def ltrim(s, prefix): if s.startswith(prefix): return s[len(prefix):] return s
sites = ['www.google.com', 'http://python.org', 'www.yahoo.com'] sites = [ltrim(site, 'http://') for site in sites]
Would there be any interest to add this helper function, as well as an "rtrim" and "trim", to the str class?
I'm against adding this as a string method, or even a a function in the stdlib.
I've done a lot of text processing with Python and have hardly ever needed something like this. If you think this would be useful often, a good way to convince this list is to show some examples of how it could improve code in the standard library, noting how common they are.
In general, having a lot of string methods is very harmful because it makes learning Python a longer and more confusing process. Furthermore, this functionality is very simple and easy to implement, I just thought of 3 different ways  to implement this function in a simple, readable one-liner. For these reasons, unless you can show that this will be very useful very often, I'm against.
 ltrim = lambda item, to_trim,: re.sub('^' + to_trim, '', item) ltrim = lambda item, x: item[0 if not item.startswith(x) else len(x):] ltrim = lambda item, to_trim: ''.join(item.split(to_trim, 1))
Ignore the third implementation, it's broken... here's another one in its place: ltrim = lambda item, x: item[item.startswith(x) * len(x):]