Delayed evaluation of csh variables?

[Harald.Eikrem at elab-runit.sintef.no]

I believe there are cases when csh outperforms Bourne shell, e.g. when you
are on a slow system and need access to expression evaluation, exemplified by:

=========
#!/bin/csh -f
# pickcolor - pick an X application background color semirandomly
if ( $#argv == 0 ) then
        set argv=( BlanchedAlmond Bisque NavajoWhite YellowGreen \
                   BlanchedAlmond Honeydew2 Tan LightSalmon LavenderBlush \
                   MistyRose Moccasin LightSteelBlue NavajoWhite PaleTurquoise \
                   BlanchedAlmond Khaki PaleGoldenrod Lavender Tan Salmon \
                   Orchid Seashell3 PaleVioletRed Thistle NavajoWhite Wheat )
endif
set pick=1
if ( $#argv > 1 ) then
        /usr/games/random -e $#argv
        @ pick = $status + 1
endif
echo $argv[$pick]
=========


For a different case, save the following as ~/csh/path and then
    alias path source ~/csh/path "'\!*'"
then you have a simple csh $path manipulator.
I like to see this done for ksh/bash......			--Harald E

=========
# csh search path management procedure
# - invoke through alias path source <thisdirectory>path "'\!*'"
#
if ( ! $?path ) set path = ""
if ( "$path" == '' && '!*' !~ [./~]* && '!*' !~ \$?* ) then
		set path = (. ~/bin /usr/local/bin /usr/ucb /bin /usr/bin)
		echo 'No path set; using default settings.\
'$path
else if ( '!*' == '' ) then
	echo $path
else if ( '!*' == '-' || '!*' == '-$' ) then
	if ( $#path == 1 ) then
		echo 'Only one path element left, will not unset $path'
	else
		@ n__ = $#path - 1
		set path = ($path[-$n__])
		echo $path
	endif
	unset n__
else if ( '!*' == '-^' ) then
	if ( $#path == 1 ) then
		echo 'Only one path element left, will not unset $path'
	else
		set path = ($path[2*])
		echo $path
	endif
	unset n__
else if ( '!*' =~ \-[1-9] || '!*' =~ \-[1-9][0-9] ) then
	@ arg__ = - !^
	if ( $arg__ > $#path ) then
		if ( $#path == 1 ) then
			echo 'There is currently only '$#path' element in $path'
		else
			echo 'There are currently '$#path' elements in $path'
		endif
	else if ( $#path == 1 ) then
		echo 'Only one path element left, will not unset $path'
	else if ( $arg__ == $#path ) then
		@ n__ = $arg__ - 1
		set path = ($path[-$n__])
		echo $path
	else
		@ n__ = $arg__ - 1
		@ r__ = $arg__ + 1
		set path = ($path[-$n__] $path[$r__-])
		echo $path
	endif
	unset arg__ n__ r__
else if ( '!*' =~ [1-9^]\ [./~]* || '!*' =~ [1-9][0-9]\ [./~]* || \
	  '!*' =~ [1-9^]\ \$[_a-zA-Z0-9]* || \
	  '!*' =~ [1-9][0-9]\ \$[_a-zA-Z0-9]* ) then
	if ( !^ > $#path + 1 ) then
		if ( $#path == 1 ) then
			echo 'There is currently only '$#path' element in $path'
		else
			echo 'There are currently '$#path' elements in $path'
		endif
	else if ( !^ <= 1 || !^ == ^ ) then
		set path = (!:2* $path)
		echo $path
	else if ( !^ > $#path ) then
		set path = ($path !:2*)
		echo $path
	else
		@ r__ = !^ - 1
		set path = ($path[-$r__] !:2* $path[!{^}*])
		echo $path
	endif
	unset arg__ n__ r__
else if ( '!*' =~ [./~]* || '!*' =~ \$[_a-zA-Z0-9]* ) then
	set path = ($path !*)
	echo $path
else echo 'Usage: path { -^ | -$ | - | -<n> | <n> pathname(s) | pathname(s) }\
meaning:\
	-^		strip first element from $path.\
	-$ or -		strip last element.\
	-<n>		strip element number <n>, numbering from 1 up.\
	<n> pathname(s)	insert pathname(s) before element <n>, where\
			<n> can be ^ if before first element.\
	pathname(s)	add pathname(s) beyond last element.\
\
A valid pathname should start with [./~], or be a shell variable constituting\
one or more valid pathnames.'
endif