[WJG] (25nd May, 2005) I expect that something like this code snippet is already somewhere on the Wiki
but I thought it worth a posting as this method allows for cleaner, simpler code.
 
[Larry Smith] This is precisely what [init] does, but init also provides
a way to initialize switches, and will disallow setting things that the
proc isn't able to understand (this is both a security thing as well as
error detection).  [init] can also parse your argv as well, if called in
the global scope.

If a proceedure has a whole range of switches then why waste time parsing the args 
list with a load of switch options or if.. else.. constructions? Just assume that 
the switch names themselves have some meaningful description within the scope of 
the calling proc, strip out the leading "-" and use the remnamt of the string as a 
variable name. 
 
As the proc documentation should always contain some explanation of the usage of 
the proceedure, its arguments and switches should be no cause for confusion.


 # -------------------------------------------------------
 # proc: 
 #     easyargs     -just a piece of demo code
 # 
 # args: 
 #     a
 #     b
 # 
 # switches:
 #     -up
 #     -down
 #     -in
 #     -out            
 # 
 # -------------------------------------------------------

 proc easyargs {a b args} {
    # read in args, set values according to switch names
    foreach {opt val} $args {
        set tmp [string trim $opt -] 
        set $tmp $val
    }
    #just to prove that the values are set...
    foreach item {up down in out} {
        puts "$item [set $item]"
    }
 }

 easyargs  red green -up 0 -down 1 -in 0 -out 1

----
See also [Named arguments]