Re: Variadic arguments to methods in Objective-C - How ?
Re: Variadic arguments to methods in Objective-C - How ?
- Subject: Re: Variadic arguments to methods in Objective-C - How ?
- From: Brendan Younger <email@hidden>
- Date: Sat, 08 Jan 2005 14:18:18 -0600
On Jan 8, 2005, at 2:04 PM, Tommy Nordgren wrote:
Jan 8, 2005 kl. 8:38 PM skrev Vincent Coetzee:
Dear List,
How does one create methods in Objective-C that use a variable number
of arguments. I am familiar with the normal C mechanism, but does
this work in Objective-C considering the hidden arguments to methods
(i.e. _self and _cmd) ? So can I use the normal C mechanism and if
not how is it done ? Some sample code would be appreciated.
As far as I know, the objective C syntax don't allow variadic
methods. However,
by giving the source files the suffix .mm, you can use C++ as well to
a certain extent, although it is tricky, and according to the
documentation not possible to embed c++ objects with virtual methods
directly in Objective C classes. You can hovever use pointers to refer
to objective c classes from c++ code and vice versa.
Also, it IS possible to embed most C++ classes in Objective C,
althought it can be tricky because there is no built in language
support for this.
Hope this helps.
Stuff and nonsense. Check out [NSString stringWithFormat:]. The idea
behind variadic arguments is exactly the same as that of C. Just thing
of your method as a function which looks like:
myMethod(id self, SEL _cmd, id arg1, ....);
In which case, your code would look something like
- (void)myMethod:(id)arg1, ... {
va_list args;
id object;
va_start(args, arg1);
while((object = va_arg(list, id))) {
// knock yourself out
}
va_end(list);
}
and of course you can change the types as you wish.
Brendan Younger
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