When I instantiate "mine" outside of the if statement, it won't change the value from within the condition. But it will execute the "set a" portion of the statement inside the condition.

output.txt

z: 45
a: 9
This is the value of z / x = 20
a: 20

scoping.tcl

set mine ""
set z 100
if {$z > 200} {
    set mine [puts "This is the value of z * x = [set a [expr {$z * $x}]]"]
} else {
    set mine [puts "This is the value of z / x = [set a [expr {$z / $x}]]"]
}
puts $a
puts "This is me storing the command in a variable, \$mine = $mine"

set mine ""
set x 5
set z 100
;#I want to make it so I store the literal value of the line before it's executed, followed by executing the line.
;#That way if you call elsewhere, the command is optionally maleable before it's executed.
if {$z > 200} {
upvar 0 mine answer
set answer {[set a [expr {$z * $x}]]}

} else {
upvar 0 mine answer
set answer {[set a [expr {$z / $x}]]}
}

expr $mine == 1
puts "mine: $mine"
puts "a has been changed: $a"

Didn't know about upvar, also I know setting to global is bad, if this was in a function I would set it to one. So I would be stepping out one level.