Libguestfs - Jul 2016 - Re: [PATCH v3 4/8] mllib: Add some imperative list manipulation functions.

On Thu, Jul 07, 2016 at 06:08:43PM +0100, Richard W.M. Jones
wrote:
> On Thu, Jul 07, 2016 at 07:00:46PM +0200, Pino Toscano wrote:
> > On Thursday 07 July 2016 17:30:03 Richard W.M. Jones wrote:
> > > This adds imperative list manipulation functions inspired by
Perl.
> > > The functions are passed list refs which get updated in place.
> > > 
> > > This allows us to replace some awkward pure functional code like:
> > > 
> > >   let xs = ys in
> > >   let xs = if foo then xs @ zs else xs in
> > > 
> > > with:
> > > 
> > >   let xs = ref ys in
> > >   if foo then append xs zs;
> > > ---
> > 
> > TBH I've always found the "shift" and
"unshift" naming of Perl
> > functions slightly awkward, but can live with them. (At least the
> > new functions do the same as Perl ones.)
> 
> I agree, but for consistency I thought it was better to keep those
> names rather than trying to think up new ones which would be different
> from everything else.
Actually I forgot that C++ (STL vector, deque etc) have functions
called push_front, pop_front, push_back, pop_back.  Don't know if that
would be better.  Is it obvious what front and back mean?

Rich.

-- 
Richard Jones, Virtualization Group, Red Hat http://people.redhat.com/~rjones
Read my programming and virtualization blog: http://rwmj.wordpress.com
virt-builder quickly builds VMs from scratch
http://libguestfs.org/virt-builder.1.html

On Fri, Jul 08, 2016 at 09:10:51AM +0100, Richard W.M. Jones
wrote:
> On Thu, Jul 07, 2016 at 06:08:43PM +0100, Richard W.M. Jones wrote:
> > On Thu, Jul 07, 2016 at 07:00:46PM +0200, Pino Toscano wrote:
> > > On Thursday 07 July 2016 17:30:03 Richard W.M. Jones wrote:
> > > > This adds imperative list manipulation functions inspired by
Perl.
> > > > The functions are passed list refs which get updated in
place.
> > > > 
> > > > This allows us to replace some awkward pure functional code
like:
> > > > 
> > > >   let xs = ys in
> > > >   let xs = if foo then xs @ zs else xs in
> > > > 
> > > > with:
> > > > 
> > > >   let xs = ref ys in
> > > >   if foo then append xs zs;
> > > > ---
> > > 
> > > TBH I've always found the "shift" and
"unshift" naming of Perl
> > > functions slightly awkward, but can live with them. (At least the
> > > new functions do the same as Perl ones.)
> > 
> > I agree, but for consistency I thought it was better to keep those
> > names rather than trying to think up new ones which would be different
> > from everything else.
> 
> Actually I forgot that C++ (STL vector, deque etc) have functions
> called push_front, pop_front, push_back, pop_back.  Don't know if that
> would be better.  Is it obvious what front and back mean?
That would be the attached patch.

Rich.

-- 
Richard Jones, Virtualization Group, Red Hat http://people.redhat.com/~rjones
Read my programming and virtualization blog: http://rwmj.wordpress.com
virt-builder quickly builds VMs from scratch
http://libguestfs.org/virt-builder.1.html

On Friday 08 July 2016 09:40:12 Richard W.M. Jones
wrote:
> On Fri, Jul 08, 2016 at 09:10:51AM +0100, Richard W.M. Jones wrote:
> > On Thu, Jul 07, 2016 at 06:08:43PM +0100, Richard W.M. Jones wrote:
> > > On Thu, Jul 07, 2016 at 07:00:46PM +0200, Pino Toscano wrote:
> > > > On Thursday 07 July 2016 17:30:03 Richard W.M. Jones wrote:
> > > > > This adds imperative list manipulation functions
inspired by Perl.
> > > > > The functions are passed list refs which get updated in
place.
> > > > > 
> > > > > This allows us to replace some awkward pure functional
code like:
> > > > > 
> > > > >   let xs = ys in
> > > > >   let xs = if foo then xs @ zs else xs in
> > > > > 
> > > > > with:
> > > > > 
> > > > >   let xs = ref ys in
> > > > >   if foo then append xs zs;
> > > > > ---
> > > > 
> > > > TBH I've always found the "shift" and
"unshift" naming of Perl
> > > > functions slightly awkward, but can live with them. (At
least the
> > > > new functions do the same as Perl ones.)
> > > 
> > > I agree, but for consistency I thought it was better to keep
those
> > > names rather than trying to think up new ones which would be
different
> > > from everything else.
> > 
> > Actually I forgot that C++ (STL vector, deque etc) have functions
> > called push_front, pop_front, push_back, pop_back.  Don't know if
that
> > would be better.  Is it obvious what front and back mean?
IMHO yes, more than "unshift" (unshift from what, for example?).
> That would be the attached patch.
LGTM -- note also the current solution is fine for me, as long as we
are using a naming already in the wild and not anything homebrew.

Thanks,
-- 
Pino Toscano