Re: [PATCH 0/3] Generalized "string function" syntax

From: Junio C Hamano <gitster@pobox.com>
Date: Oct 18, 2009, 04:18 UTC
Message-ID: <7v63ad5o8p.fsf@alter.siamese.dyndns.org>
In-Reply-To: <4ADA3153.7070606@lsrfire.ath.cx>

René Scharfe <rene.scharfe@lsrfire.ath.cx> writes:

Show 18 quoted lines

> Junio C Hamano schrieb:
>> I mentioned an idea to enhance the pretty=format language with a
>> string function syntax that people can extend by adding new functions
>> in one of the "What's cooking" messages earlier.  The general syntax
>> would be like
>> 
>> %[function(args...)any string here%]
>> 
>> where "any string here" part would have the usual pretty=format
>> strings. E.g.  git show -s --format='%{w(72,8,4)%s%+b%]' should give
>> you a line wrapped commit log message if w(width,in1,in2) is such a
>> function.
>
> I pondered line wrapping with format strings briefly a long time ago, and
> I always considered it to be more similar to a colour, i.e. a state that
> one can change and that is applied to all following text until the next
> state change.  (Except that it's always reset at the end of the format
> string.)  The example above would then turn into '%w(72,8,4)%s%+b'.

As a syntax to express "wrapping" behaviour alone, I think this is much simpler and more superiour. I guess with this if you want to wrap something to 72 columns and then wrap something else to 66 columns, you would write '%w(72,8,4)something%w(66,8,4)something else', right?

I used %] only for two reasons.

 - Without an explicit "here it ends", I couldn't come up with a good way
   to express '%[w(72,8,4)something%]something else'.  IOW, how I can say
   "wrap something to 72 columns and then place something else without any
   wrapping"?
   
 - When we need to support more than one string function like this, it is
   unclear what '%f()one string%g()another one' in your syntax means.
   Does it mean '%[f()one string%]%[g()another one%]' (i.e. concatenate
   the result of applying string function f to 'one string' and the result
   of applying string function g to 'another one')?  Or does it mean
   '%[f()one string%[g()another one%]%]' (apply 'f' to concatenation of
   'one string' and the result of applying 'g' to 'another one')?