On Monday, 22 July 2013 at 12:08:06 UTC, Nick Treleaven wrote:
Hi,
I remember an example in some slides by Walter which had this
snippet (slightly simplified):
stdin.byLine.map!(l => l.idup).array
Someone commented in a reddit post that the idup part was not
intuitive (can't find the link now, sorry).
I made a pull request to re-enable using byLine!(char,
immutable char). (Note this compiled in the current release,
but didn't work properly AFAICT. It did work by commit
97cec33^).
https://github.com/D-Programming-Language/phobos/pull/1418
Using that allows us to drop the map!(l => l.idup) part from
the above snippet. The new syntax isn't much better, but it can
also be more efficient (as it caches front). I have an idea how
to improve the syntax, but I'll omit it for this post.
I've since thought that if most or all lines in a file need to
be persistent, it may be more efficient to use
readText(filename).splitLines, because that doesn't need to
allocate for each line.
There are two enhancements for that approach:
1. readText should accept a File, not just a filename, so we
can use stdin.
2. splitLines makes an array. It would be more flexible to have
an input range created from a function e.g. lineSplitter.
With these enhancements, we could change the byLine docs to
recommend using File.readText.lineSplitter if most lines need
to be persistent.
Thoughts?
I remember seeing Walter's component programming example and
feeling that the idup stuck out like a sore thumb.
I like the idea. Makes simple programs even simpler without
sacrificing performance by changing byLines. Ideally readText
would take generic streams rather than Files but that will have
to wait until std.io gets finished.
