[REBOL] Re: How to check function arguments ?
From: jason:cunliffe:verizon at: 9-Jun-2002 1:11
Hi Romano and everyone
> somefunc: func [inp [any-type!]] [if value? 'inp [print [inp * 3.14159]]]
..damn that's clever.. thanks!
It's a very interesting idiom the way it depends upon those two quite different
but crucial parts
any-type!
'inp
Doing quite a lot of Vanilla programming, so it's sometimes cgi, some times
internal functions. But the more flexible the args, the better - you don't have
to remember, and it makes modular API development easier. Before REBOL, I was in
love with Python, which has some great features for function args:
1. Keyword arguments with defaults
2. - Variable Length arguments
Here's an example from Core Python Programming by Wesley Chun [good book]
def tupleVarArgs(arg1, arg2='defaultB', *theRest)
'display regular args and non-keyword variable args'
print 'formal arg1:', arg1
print 'formal arg2:', arg2
for eachXtrArg in theRest:
print 'another arg:', eachXtrArg
When a double ** is used it signifies variable Keyword arguments [Python
Dictionary].
Python dicts are close to REBOL blocks depending how you use them, so I guess
variable keyword args could be done with a combination of REBOL's refinements
and some other magic.
REBOL makes one work harder for the defaults. Perhaps you already know some more
cool idioms ;-)
thanks
./Jason
