upvar problem 1

[marsd]

I am not catching some of the nuances of passing variables
between stacklevels here..if someone could explain what I
am doing wrong I would appreciate it;-)

If I have code that looks like this:
#script main

set R 12

proc echo_val {N} {
upvar #0 $N loc
puts "Local value of proc arg $N is $loc"
}

echo_val $R
#end

"Error is can't read loc, no such variable."

Which seems pretty bizarre to me since from what
I understand upvar aliases point to a value up the stack.
I have also read that the statement upvar #0 is
equivalent to the global declaration.
I have used upvar with the tcl_http package with no
problem so this simple translation of variable aliases
is baffling me.
Does the upvar alias have to exist in the same scope
as the original var?

 

[ulis]

You only need to replace
echo_val $R
by
echo_val R

You must pass to echo_val the name of the global variable, not its value.

ulis

 

[marsd]

Geez, what a lamebrain trick.

You saved me a rewrite.

Thanks Ulis.