Parallel Assignment
Some programming languages, such as JavaScript (since 1.7), Lua, occam 2, Perl, Python, REBOL, Ruby, and Windows PowerShell allow several variables to be assigned in parallel, with syntax like:
a,b := 0,1
which simultaneously assigns 0 to a and 1 to b. If the right-hand side of the assignment is an array variable, this feature is sometimes called sequence unpacking:
var list := {0, 1}
a,b := list
The list will be unpacked so that 0 is assigned to a and 1 to b. More interestingly,
a,b := b,a
Swaps the values of a and b. In languages without parallel assignment, this would have to be written to use a temporary variable
var t := a
a := b
b := t
since a:=b ; b:=a leaves both a and b with the original value of b.
Parallel assignment was introduced in CPL in 1963, under the name simultaneous assignment.
Read more about this topic: Assignment (computer Science)
Famous quotes containing the word parallel:
“One writes of scars healed, a loose parallel to the pathology of the skin, but there is no such thing in the life of an individual. There are open wounds, shrunk sometimes to the size of a pin-prick but wounds still. The marks of suffering are more comparable to the loss of a finger, or the sight of an eye. We may not miss them, either, for one minute in a year, but if we should there is nothing to be done about it.”
—F. Scott Fitzgerald (1896–1940)