[REBOL] Re: a new switch-like flow-control function
From: lmecir:mbox:vol:cz at: 23-Dec-2003 16:59
Hi Alain,
>Here is a function for only 1 condition but 3 cases : if it can be
>useful to anyone
>
>trif: func [
>
>...
>
>; example:
>print trif request "give an answer" ["yes"]["no"]["cancel"]
>
>by the way,
>is it good that "not none" equals "true" ?
>
>Alain Goyé.
>
yes, it is useful. The following improvement uses the [throw] attribute
to make the behaviour of the function more standard with respect to Return:
trif: func [
{Three case if}
[throw]
condition
iftrue [block!]
iffalse [block!]
ifnone [block!]
] [
do either condition [
iftrue
] [
either none? condition [
ifnone
] [
iffalse
]
]
]
; example:
f: does [trif request "give an answer" [return "yes"] [return "no"] [return "cancel"]
"Shoudn't get here"]
Merry Christmas
-Ladislav
