lvarpop var ?indexExpr? ?string?
The lvarpop command pops (deletes) the element indexed by the
expression indexExpr from the list contained in the variable
var. If index is omitted, then 0 is assumed. If string is
specified, then the deleted element is replaced by string. The
replaced or deleted element is returned. Thus
lvarpop argv 0
returns the first element of argv, setting argv to contain
the remainder of the string.
If the expression indexExpr starts with the string "end", then
end is replaced with the index of the last element in the
list. If the expression starts with "len", then len is replaced
with the length of the list.
See also lvarpush.
Category Command, a part of Tclx