On Thursday, August 31, 2017 18:43:40 Jesse Phillips via Digitalmars-d-learn wrote: > On Thursday, 31 August 2017 at 18:26:33 UTC, Sergei Degtiarev > > wrote: > > Hi, > > I tried to create a simple range concatenating several files, > > > > something like this: > > File[] files; > > .... > > foreach(ln; joiner(files.map!(a => a.byLine))) > > > > writeln(ln); > > > > and I see every first line of each file is missing. > > > > However, when I do same thing with separator: > > char[][] separator=["**** new file ****".dup]; > > foreach(ln; joiner(files.map!(a => a.byLine), separator)) > > > > writeln(ln); > > > > everything works fine, both separator and first lines are > > printed. > > It looks pretty much as a bug for me, but I'm not sure I use it > > correctly. > > Doesn't byLine() reuse a buffer, joiner probably caches the first > line and calls .popFront()
In general, byLine does not work with other range-based algorithms precisely because it reuses the buffer. I think that it does manage to work for some, but IMHO, it should have just supported foreach via opApply and not been a range at all. It's great for efficiency in a loop but horrible for range chaining. Folks get bit by this problem all the time. Fortunately, we now have byLineCopy which actually uses a separate dynamic array for each line, but even still, often, someone grabs byLine and then gets weird behavior that they don't understand. - Jonathan M Davis
