TCL coming up with a general code - tcl

Question

I am using tcl. Below is the code I have so far; is there a better way to do this?
if {$parname == "Wbay1" || $parname == "Wbay2" } {
set count [string index $parname end]
set Wbay$count [lindex $elem 1]
puts "set Wbay$count [lindex $elem 1]"
}
Be more general like this
if {$parname == "Wbay*" } {
set count [string index $parname end]
set Wbay$count [lindex $elem 1]
puts "set Wbay$count [lindex $elem 1]"
}

Answer 1

If the names are Wbay1, ..., Wbay9, you can use
if {[string match {Wbay[1-9]} $parname]} {
set $parname [lindex $elem 1]
}
If the number part can be greater than 9, you should use
if {[regexp {Wbay\d+} $parname]} {
set $parname [lindex $elem 1]
}
A regexp (regular expression) match is more powerful than a string match. In this case, \d+ means "one or more digits".
If you want to record the highest number you've seen so far, use
set maxN 0
...
if {[regexp {Wbay(\d+)} $parname -> n]} {
set maxN [expr {max($n, $maxN)}]
set $parname [lindex $elem 1]
}
The parenthesis means that you want to capture the matched string within, i.e. the number. The -> symbol is a variable name: it's a convention that is often used to store the full match (e.g. "Wbay7") when we don't care about it. The variable n is set to the number that was captured. If regexp doesn't return 1, the value in n can't be trusted: the variable will keep whatever value it had before. The variable maxN is set to whichever of $n and $maxN is greatest.
But you might also find an array variable useful. With an array, you name the individual members Wbay(1), Wbay(2), Wbay(99), etc (they don't have to be consecutive or in order). If you want to know how many members you have, array size Wbay will tell you.
Documentation:
array,
expr,
if,
lindex,
max (function),
regexp,
set,
string,
Syntax of Tcl regular expressions
Syntax of Tcl string matching:
* matches a sequence of zero or more characters
? matches a single character
[chars] matches a single character in the set given by chars (^ does not negate; a range can be given as a-z)
\x matches the character x, even if that character is special (one of *?[]\)