Why ByChunk is not regnize by st.range.takeOne and why Section has no value

[bioinfornatics via Digitalmars-d-learn]

On Monday, 3 November 2014 at 06:43:50 UTC, Ali Çehreli wrote:
> On 11/02/2014 04:58 PM, bioinfornatics wrote:
>
> > Dear,
> > Some problem to build this code:
> http://fpaste.org/147327/75948141/
> >
> >
> > $ ldc2 fasta_test.d
> > /usr/include/d/std/range.d(3605): Error: template
> std.array.save
> > cannot deduce function from argument types !()(ByChunk),
> > candidates are:
>
> I think that is due to the too permissive template constraint 
> of takeOne in phobos/std/range.d. Even though it say 
> "isInputRange!R", it clearly needs "isForwardRange!R" because 
> it calls .save() on that range:
>
>     @property auto save() { return Result(_source.save, empty); 
> }
>
> So, the following is wrong:
>
>   auto takeOne(R)(R source) if (isInputRange!R)
>
> It should be:
>
>   auto takeOne(R)(R source) if (isForwardRange!R)
>
> If you modify range.d locally to require ForwardRange, you will 
> see that your following call will get an error message because 
> byChunk is not a ForwardRange:
>
>         // Take a piece of byte from current file
>         ubyte[] buffer =  takeOne(inputRange);
>
> I think this issue is already reported as a part of the 
> following bug:
>
>   https://issues.dlang.org/show_bug.cgi?id=9724
>
> Ali

Ok but I do not see why to use save method for a takeOne function
is possible to write this function without to use it