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Top Forums Shell Programming and Scripting How to evaluate a variable name on LHS of expression? Post 302886928 by DJR on Tuesday 4th of February 2014 09:04:07 AM
Old 02-04-2014
Chubler_XL -

Thank you - your solution works perfectly - does exactly what I need. But I don't understand why. I thought the "export" statement just made a local variable global to where it was called from. And in searching a bit on it that's what everything I've found says it does. So I tried removing it, thinking maybe just the way you quoted the rest of the statement is what did it, but it errors if I remove "export" from the line, and if I echo that variable even inside the function it does not assign it a value. So obviously that doesn't just change the scope, it changes how the line is evaluated. For my own knowledge, can you explain what is going on that makes this work?

Thanks for your help,

Doug
 

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lassign(n)						       Tcl Built-In Commands							lassign(n)

__________________________________________________________________________________________________________________________________________________

NAME
lassign - Assign list elements to variables SYNOPSIS
lassign list varName ?varName ...? _________________________________________________________________ DESCRIPTION
This command treats the value list as a list and assigns successive elements from that list to the variables given by the varName arguments in order. If there are more variable names than list elements, the remaining variables are set to the empty string. If there are more list elements than variables, a list of unassigned elements is returned. EXAMPLES
An illustration of how multiple assignment works, and what happens when there are either too few or too many elements. lassign {a b c} x y z ;# Empty return puts $x ;# Prints "a" puts $y ;# Prints "b" puts $z ;# Prints "c" lassign {d e} x y z ;# Empty return puts $x ;# Prints "d" puts $y ;# Prints "e" puts $z ;# Prints "" lassign {f g h i} x y ;# Returns "h i" puts $x ;# Prints "f" puts $y ;# Prints "g" The lassign command has other uses. It can be used to create the analogue of the "shift" command in many shell languages like this: set ::argv [lassign $::argv argumentToReadOff] SEE ALSO
lindex(n), list(n), lset(n), set(n) KEYWORDS
assign, element, list, multiple, set, variable Tcl 8.5 lassign(n)
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