if 0 { I needed a switch command with variables in place of constants
Here is the result.
I added list of values in place of one value, and expression.
I used case, CASE and default to name the needed internal procs.
syntax is:
select value \
{
case list_of_values script
...
?default script?
}
or
select \
{
case expr script
...
?default script?
}
default fires always so must be last (no check).
As an added benefice you can put comments (or other commands)
ulis
}
# the select proc
proc select {args} \
{
proc default {body} { uplevel 1 $body }
set expr 0
switch [llength $args] \
{
1 \
{ # case expr
proc case {expr body} \
{
if {[uplevel 1 expr $expr]} \
{ uplevel 1 $body; return -code return }
}
uplevel 1 [lindex $args 0]
}
2 \
{ # case list
proc CASE {value list body} \
{
if {[lsearch $list $value] != -1} \
{ uplevel 1 $body; return -code return }
}
set value [lindex $args 0]
set body [lindex $args 1]
interp alias {} case {} CASE $value
uplevel 1 $body
}
default \
{ error "syntax is select ?value? body" }
}
rename CASE ""
interp alias {} case {}
rename default ""
}
# some test cases
set value key4
foreach i {1 2 3} { set key$i key$i }
select $value \
{
puts "value $value"
# test for keys
case key0 { puts "found key0" }
case $key1 { puts "found $key1" }
case [list $key2 $key3] { puts "found $key2 or $key3" }
case {key4 key5} { puts "found key4 or key5" }
# default case
default { puts "$value is not a valid key" }
}
set value 0
select \
{
puts "value $value"
case {$value < 0} { puts "negative value" }
case {$value > 0} { puts "positive value" }
case {$value == 0} { puts "null value" }
}