I don't know if anyone will be very interested in this, but here is
another little hack that I dreamed up this weekend in an effort to
create a single .esrc for every architecture that I commonly use.
It isn't exactly blazingly fast (it adds about 1 second onto my login
time), but it is pretty useful.
The following function, build-fn, is used to dynamically build a
function, or alias, based off of a selection of similarly functional
programs. The best way to describe this is using a couple of
examples:
build-fn play player splayer play \
default {for (file = $*) {cat $file > /dev/audio}}
This will cause a new function 'play' to be created (actually, $fn-play);
say player exists in your $path (in /usr/audio/bin, like it does on my
system), then:
; echo $fn-play
@ * {/usr/audio/bin/player $*}
If player doesn't exist in your path, but splayer does exist in
/usr/local/bin, then:
; echo $fn-play
@ * {/usr/local/bin/splayer $*}
If there are no matches, then you get the following:
; echo $fn-play
@ * {for(file=$*){%create 1 <={%one /dev/audio} {cat $file}}}
build-fn also allows you to override the default function created for
programs that it manages to find. For example:
build-fn ll ll { @prog@ -F $* } \
ls { @prog@ -lF $* }
So, if you actually have a program called ll on your system (I do,
in /bin), then:
; echo $fn-ll
@ * {/bin/ll -F $*}
If ll doesn't exist in your path, then:
; echo $fn-ll
@ * {/bin/ls -lF $*}
Note, that any instances of @prog@ in your supplied code fragment
are replaced with the full path name of the program that matched within
your list.
Caveats:
o You can't search for a program called 'default'.
o It doesn't make sense supply @prog@ within a default
selection.
o You can't stop @prog@ from being expanded within a code
fragment.
Have fun!
-scott
--
_/ _/ _/_/_/ _/_/_/_/ _/_/_/ Scott C. Gray (gray@nas.nasa.gov)
_/_/ _/ _/ _/ _/_/ _/ _/ NASA Ames Research M/S 258-6
_/ _/_/ _/_/_/_/ _/_/ _/_/_/_/ For PGP public key, send me mail
_/ _/ _/ _/ _/_/_/_/ _/ _/ with subject line of "PGP request".
----------------------------[ CUT HERE ]-----------------------------------
fn choose-bin bin-list {
for ( bin = $bin-list ) {
for ( dir = $path ) {
if { access -rx $dir/$bin } {
return $dir/$bin
}
}
}
return
}
# build-fn function-name { prog-name | default } [script] ...
#
# This function is used to dynamically build a function, or alias,
# using the first occurance of prog-name that actually exists.
fn build-fn function-name args {
let (
default-fn = # script specified by the default key word
prog-name = # current program we are searching for
prog-name-full = # fully specified program path
prog-script = # script to be used if prog-name is found
dir = # variable used in a loop
success = false
) {
while { ! ~ $#args 0 } {
prog-name = $args(1)
if { ~ $args(2) '{'*'}' } {
prog-script = $args(2)
args = $args(3 ...)
} {
prog-script =
args = $args(2 ...)
}
if { ~ $prog-name default } {
if { ~ $#prog-script 0 } {
throw error build-fn 'build-fn: No code with default'
}
default-fn = $prog-script
} {
prog-name-full = <={ choose-bin $prog-name }
if { ! ~ $#prog-name-full 0 } {
if { ~ $#prog-script 0 } {
prog-script = '@ * {'^$prog-name-full^' $*}'
} {
prog-script = '@ *' `{echo $prog-script | \
sed -e 's,@prog@,'^$prog-name-full^',g'}
}
fn-$function-name = $^prog-script
success = true
break
}
}
}
if { ! ~ $success true } {
if { ! ~ $#default-fn 0 } {
default-fn = '@ * ' ^ $^default-fn
fn-$function-name = $^default-fn
} {
throw error build-fn 'build-fn: No match for '^$function-name
}
}
}
return 0
}
--
_/ _/ _/_/_/ _/_/_/_/ _/_/_/ Scott C. Gray (gray@nas.nasa.gov)
_/_/ _/ _/ _/ _/_/ _/ _/ NASA Ames Research M/S 258-6
_/ _/_/ _/_/_/_/ _/_/ _/_/_/_/ For PGP public key, send me mail
_/ _/ _/ _/ _/_/_/_/ _/ _/ with subject line of "PGP request".