a word about shift

a word about shift

[malte]

I'd like to raise a discussion about shift's behaviour.
There are two things I am not too content with:

    1) shift doesn't work on any other variables than *
    What about an extended shift, say shift var number,
    or shift number, where the latter assumes * is to be shifted.
    This preserves compatibility.

    2) When $#var is lower than the number of shifts, shift prints an
    error message and does nothing. I'd prefer shift would optionally
    a) just print an error message, 
    b) print an error and set var to (),
    c) be silent and set var to (),
    d) do nothing

What about this? Anyone experienced out there?


_______________________________________________________________________________
malte@techfak.uni-bielefeld.de

send mail to:	Universitaet Bielefeld, Technische Fakultaet
		z. Hd. Malte Uhl
		Postfach 8640
		4800 Bielefeld 1

Re: a word about shift

[Chris Siebenmann]

 One can write a shift function that shifts an arbitrary list (except '*')
by whatever you want; in fact, I've attached my version at the end of this
message. Given that, I don't think we need to augment shift.

 I like shift giving you an error when you try to shift to far; people
who want other behaviors can write wrappers for it. I particularly dislike
options for what shift does; it should do *one* thing, always. See previous
arguments in the mailing list over options.

	- cks

# 'supershift' function for rc.
# usage:
#	sshift varname
#	sshift varname number
# shifts the list varname by number (default 1) positions.
fn sshift { if (~ $#* 1 ) { _sshift $1 1 $$1 } else { _sshift $1 $2 $$1 } }

# this function does most of the work.
# _sshift NAME COUNT LISTELEMS
# shift LISTELEMS COUNT items left, and assign the result to NAME.
fn _sshift { _vn=() { _vn=$1; shift; shift $1; shift; $_vn=$* } }