Re: [Libguestfs] [PATCH v6 2/3] mllib: modify nsplit to take optional noempty and count arguments

On Tue, Jan 31, 2017 at 01:17:12PM +0100, Tomáš Golembiovský wrote: > On Tue, 31 Jan 2017 11:35:01 +0000 > "Richard W.M. Jones" <rjones(a)redhat.com&gt; wrote: > > > On Mon, Jan 30, 2017 at 10:43:15PM +0100, Tomáš Golembiovský wrote: > > > Added two new optional arguments to nsplit: > > > > > > * keep_empty: if set to false empty elements are not stored in the > > > returned list. The default is to keep the empty elements > > > > The ?keep_empty flag is pointless. It's simpler and more > > clear to write: > > > > List.filter ((<>) "") (nsplit ...) > > > > when you don't want empty elements. > > That's not entirely true when keep_empty is used in combination with > count. When keep_empty is false then the split is not considered a > (successful) split and internal state of count is not decreased. > > Example: > > # List.filter ((<>) "") (nsplit ~count:3 "," "a,,,b,,,c,,d" ) ;; > - : string list = ["a"; "b,,,c,,d"] > > # nsplit ~keep_empty:false ~count:3 "," "a,,,b,,,c,,d" ;; > - : string list = ["a"; "b"; "c"; ",d"] IMHO that shows how ?keep_empty is a very complex interface that's difficult for ordinary programmers to understand.

Rich. -- Richard Jones, Virtualization Group, Red Hat http://people.redhat.com/~rjones Read my programming and virtualization blog: http://rwmj.wordpress.com Fedora Windows cross-compiler. Compile Windows programs, test, and build Windows installers. Over 100 libraries supported. http://fedoraproject.org/wiki/MinGW