Usage of namespace/uplevel/global in TCL

Question

I have a script like this :

proc subProc1 { } {
    puts $var1
}
proc subProc2 { } {
    puts $var2
}

proc mainProc { args } {
    # Define many variables
    subProc1
    subProc2
    #etc.
}

I would like subProc1 and subProc2 to have variables defined in mainProc. I can pass them as arguments, but it is a lot of argument, I'd like to avoid that.

I tried to use the upvar command, by adding this line to me subProcs :

subProc1 { } {
    upvar $var1 var1 $var2 var2 ;#etc
    puts $var1
    # etc.
}

But I have the "no such variable" error message, and it not nice to have a huge line like this

I just read about namespace but I don't really understand how to use this (plus I am not sure to understand the concept, so is it really adapted to my use case ?)

Answer 1

upvar is the right tool for that. The other commands can be emulated with upvar.

But you do a mistake how you call upvar. You have to use the variable name, not it's value (which will throw an "no such variable" error).

upvar var1 var1 var2 var2 ;#...

I'd think about using some different way to store the data, maybe a dictionary or an array?
This would make it easier to pass the variables.