lappend varName ?value value ...?
http://www.purl.org/tcl/home/man/tcl8.4/TclCmd/lappend.htm
Appends each value as a list element onto the end of the list stored in varName.
lappend used to be the only list-command which requires the name of a variable containing a list rather than the list itself, but in Tcl 8.4 the lset command was introduced.
lappend listName
rather than
lappend $listName
This command differs from append in that values are appended as list elements rather than raw text.
lappend will not make varName a list ; if it is one before the command, it will continue to be one.
AJD Uh? lappend *will* attempt to make varName's value into a list. The docs say "This command treats the variable given by varName as a list." ie. if it isn't a list to begin with, tcl will attempt to convert it to one, giving an error this is not possible:
% set x "a \{" ;# string
a {
% lappend x b ;# treat it as list
unmatched open brace in list ;# it wasn't a proper list!
You do not need to assign the results of lappend to varName; lappend modifies varName directly.
How would one append an item to the beginning of a list? Since append means to the end of, one wouldn't append to the beginning of a list. Instead, for a way to perform the equivalent of prepend, see linsert -- jfr
TV (Oct 26 '04) Just because I happened to stumble accross this:
(Tcl) 98 % set r {}
(Tcl) 99 % lappend r {1 2}
{1 2}
(Tcl) 100 % set r {1 2}
1 2
You "stumbled across" proper list quoting? What? The first $r is a list with one element: "1 2" The second $r is a list with two elements: "1" and "2" Exactly the way it is supposed to be.
TV Says who ? Well anyhow, I though it was worth noticing. Evaluation assumptions in terms of list seperator characters is a convention matter, which the above writer should know if he/she were aware of various languages doing this stuff, it must be pleasent for that person that that works according to their preference.
See also list, lindex, linsert, llength, lrange, lreplace, lsearch, lsort .
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