lassign(3tcl) Tcl Built-In Commands lassign(3tcl)
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NAME
lassign - Assign list elements to variables
SYNOPSIS
lassign list ?varName ...?
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DESCRIPTION
This command treats the value list as a list and assigns successive el-
ements from that list to the variables given by the varName arguments
in order. If there are more variable names than list elements, the re-
maining 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 ana-
logue of the “shift” command in many shell languages like this:
set ::argv [lassign $::argv argumentToReadOff]
SEE ALSO
lindex(3tcl), list(3tcl), lrange(3tcl), lset(3tcl), set(3tcl)
KEYWORDS
assign, element, list, multiple, set, variable
Tcl 8.5 lassign(3tcl)
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