Re: [boost] Interest in super string class?

From: Shunsuke Sogame (mb2act_at_[hidden])
Date: 2006-07-04 05:04:40

Jeff Garland wrote:
>>>> The following is possible today:
>>>>
>>>>      std::string dst = range_construct(rng|to_upper);
>>>>      range_copy(rng|to_upper|to_lower|to_upper, dst);
>>>>
>>>> Note that '|to_upper' is lazy.
>>> I have no idea what this code does?  Construct a range from chars that have 
>>> been upper-cased and write it into dst.  Then copy the rng to while converting 
>>> it to upper, then lower, then upper?  This one isn't winning me over with code 
>>> clarity...
>> '|to_upper' makes a range of 'transform_iterator'.
> 
> Honestly, that didn't clear it up for me.  What does the rest of it do?  This 
> code doesn't make sense to me:   'to_upper|to_lower|to_upper'
> It's upper, then lower, then upper -- huh?

'to_upper` is called a range adaptor.
The pitiful iterators do what you mentioned.
That code is somewhat kidding. :-)

>>>> Well, IMHO, I prefer free-functions for another readability:
>>>>
>>> or
>>>      s1.replace_all(s2, s3);  //obvious which string is modified here
>>>
>>> Of course, you want to be able to work consistently so you have to pull along 
>>> the functions with less arguments too.
>  >
>> The main problem is that 's1' must be a 'super_string'.
> 
> Yep that's true it does.  But, you know, that's what I'm writing code for -- 
> strings of chars.  I don't really need the particular code I'm writing to 
> handle every possible type in the world -- just strings of chars.  If you 
> aren't processing strings, then don't use super_string. Pavol and John have 
> taken care of all the generic cases.  I'm reducing things down to the common 
> and frequent thing that I need to do.  And the thing is, there's still nothing 
> stopping me from writing
> 
>     super_string s(...);
>     some_free_function_algorithm_here(s, ...);
> 
> So what have I lost?  Nothing.  I've gained cleaner, clearer code for the 
> things I do every day -- code I can explain to any programmer.  There isn't a 
> single novel algorithm or function in super_string -- I've just optimized the 
> generic code for the common cases I need by wrapping up a couple of existing 
> Boost libraries.

Right. 'super_string' can be used as 'Sequence' and 'Range'.
IIRC, I see your proposal is no radical and
related to the language feature proposal
which makes users have the choice of:

     'foo(a);' or 'a.foo();'

>> The 'Range' and 'Sequence' abstractions will disappear.
>> How does this look? :-)
>>
>>      replace_all(out(s1), in(s2), in(s3));
> 
> Better, but it's still ugly in comparison.  I could give the first one to just 
> about any programmer (even non-c++) and they would get it.  With your example 
> I'm sure lots of programmers will be scratching there heads.  They'll be 
> distracted by the 'in' and 'out'.  I certainly am.

I agree we should appreciate non-c++ programmers.
Actually range adaptors looks influenced by unix pipe syntax.

-- 
Shunsuke Sogame