Phobos usability with text files

[bearophile]

Michel Fortin:

> > But you don't need a new string for each line to evaluate max over line 
> > lengths; the current byLine works.
> 
> That's true.	
> 
> 
> > Generally I think buffer reuse in byLine() is too valuable to let go.
> 
> I also agree it's wasteful.

See my answers to Andrei.


> But I think bearophile's experiment has illustrated two noteworthy 
> problems. The first issue is that calling filter! on the 
> already-consumed result of byLine() gives you a seg fault. I reproduced 
> this locally, but haven't pinpointed the problem.

Maybe beside that one there is yet another problem, I have had problems in creating a version that opens and scans the file twice.


> The second one is this:
> 
> 	array(file.byline())
> 	
> which gives a wrong result because of the buffer reuse. Either it 
> should not compile or it should idup every line (both of which are not 
> entirely satisfactory, but they're better than getting wrong results).

I don't agree. dupping every line is like performing a limited deep-dup, and this is not the job of array().
Not compiling again is not the job of array(). So the problem needs to be solved elsewhere, array() is OK, I think.


> I think a range should be able to express if the value can be reused or 
> not. If the value can't be reused, then the algorithm should either not 
> instantiate, or in some cases it might create a copy.

Generally in a nonfunctional language iterables need to exhaust :-)

Bye,
bearophile