Issue 639307: new string method -- format (original) (raw)

Created on 2002-11-16 12:20 by exarkun, last changed 2022-04-10 16:05 by admin. This issue is now closed.

Messages (5)
msg41683 - (view)	Author: Jean-Paul Calderone (exarkun) *	Date: 2002-11-16 12:20
Attached patch adds a method, 'format', to str and unicode types. The method performs the same operation as the string interpolation operator. The patch also includes modifications to test_format.py as well as libstdtypes.tex (tex code untested - I can't figure out latex; hopefully it is correct though, much is copy/pasted from elsewhere). Aside from having wanted this method forever, one of my use cases is building a list of objects to be displayed in a somewhat generic fashion. Currently an explicit function is required for the simple operation of string interpolation, either by def'ing one or using a lambda, while other, more complex operations. Example attached.
msg41684 - (view)	Author: Jean-Paul Calderone (exarkun) *	Date: 2002-11-16 12:28
Logged In: YES user_id=366566 Promised example.
msg41685 - (view)	Author: Martin v. Löwis (loewis) *	Date: 2002-11-16 16:42
Logged In: YES user_id=21627 There should be one-- and preferably only one --obvious way to do it. The advantage of adding this method is not clear; you can easily achieve the same effect with class BoundMod: def __init__(self, obj): self.obj = obj def __call__(self, otherarg): return self.obj % otherarg ... def getDisplayList(self): return [ BoundMod('Link'), self.complexOutput ] Alternatively, lamda x:'Link' % x has the same effect. If you still want that feature, I suggest that you write a PEP. There are a number of alternatives to consider, for example calling the method __mod__.
msg41686 - (view)	Author: Terry J. Reedy (terry.reedy) *	Date: 2002-11-17 18:09
Logged In: YES user_id=593130 From reading the one sentence description, it was not clear to me whether .format() was to be method of a format string or a string to be formatted. Adding formstring.format(*args) as a synonym for formstring % args doesn't make much obvious sense. Besides the redundancy, I dislike this because this special-purpose method would only be valid for the small subclass of strings that are validly used as format strings. On reading the patch, the above seems to be the proposal. From the example, the point seems to be to make it easier to curry the % operator (ie, bind it to its first argument). Better to me is to leave the language alone (there are hundreds of such shortcuts that *could* be added) and either write a factory function returning bound function (via a nested definition) or a string subclass.
msg41687 - (view)	Author: Martin v. Löwis (loewis) *	Date: 2002-11-17 20:37
Logged In: YES user_id=21627 Terry, thanks for your comments. It becomes clear that such a change would meet considerable resistance in the community. So I reject this patch now; kuran, if you want to see that feature in Python, you will have to write a PEP.