Object Instances

[Will Oram]

Another source told me a reason I'm goofing on my program (see 'Absurdly
Easy Cocoa Question') is that I'm not calling instance methods on object
instances. In fact, I didn't create any instances.

BUT...various nib-based program models I'm using for my program don't have
this line:


NSObject *object = [[NSObject alloc] init];

and I assume therefore don't create instances. Yet they use instance methods
and work error and warning free.

For example, Apple's currency converter has no sign of object instances:
[url]http://developer.apple.com/documentation/Cocoa/Conceptual/ObjCTutorial/chapt[/url]
er03/chapter_3_section_7.html

What gives? Thanks.

--
"love is
the search beneath one's spamguy **at** foxchange(.)com
tiny expectations"

[Eric Pepke]

Will Oram <spamguy@ihate.spammers.com> wrote in message news:<BB2E0B61.A8E0%spamguy@ihate.spammers.com>...

> Another source told me a reason I'm goofing on my program (see 'Absurdly
> Easy Cocoa Question') is that I'm not calling instance methods on object
> instances. In fact, I didn't create any instances.
>
> BUT...various nib-based program models I'm using for my program don't have
> this line:
>
>
> NSObject *object = [[NSObject alloc] init];

Nibs do create instances. However, the way they create them is somewhat different.

[Will Oram]

On 7.7.2003 11.21 AM, in article tph-2D90C1.10213407072003@localhost, "Tom
Harrington" <tph@pcisys.no.spam.dammit.net> wrote:

I was admittedly rather vague with my generic code example, so I need to
clarify.

> Assuming that "Object" is the name of the class,

It's not; it's the instantiated class from the nib. I realised I omitted a
description of it after I posted -- sorry. Nevertheless the header I've
always been using is effectively similar to your

>
> - (int) calcNewValue:(int)currentValue;

---

>>
>> ** Actually I get three warnings:
>> - the one I mentioned
>> - return type for the method defaults to id (but the variable it returns is
>> an integer!)

>
> This is the default when no method signature is found; just as C
> defaults to assuming an undeclared function returns int, Obj-C defaults
> to assuming that an undeclared method returns id. The method doesn't
> return int because (as I explained above) it doesn't exist in the form
> that you're trying to call.

It should be. If Object is an instance created from a nib-created class,
then wouldn¹t the header I normally use (the one above) work?

>
> I think maybe you need to sit down and read up a bit on object-oriented
> programming, and on Cocoa and Objective C.

I was a tad ambiguous last post, so it no doubt confused you. But don't be
ready to call me not well-read just yet...that's why I have Cocoa
documentation, an O'Reilly text, various printouts, and Apple's online texts
at close hand at all times when I work. These don't do anything if I don't
try the code! Heck, the only way I learned Carbon was a) Macintosh-C, b)
this newsgroup, and c) toying around.

Thanks.

--
"love is
the search beneath one's spamguy **at** foxchange(.)com
tiny expectations"

[Will Oram]

An update now.

I tried the alternative header (for class methods) and it worked. But this
goes against what I asked earlier about nibs and objects, doesn't it?
Quoting you, Mr. Harrington:

"You can create your instances in Interface
Builder, if it's appropriate to the situation."

'Object' in my code, in this case, happens to be an instantiated controller
object. Shouldn't it receive instance, not class, methods then?

Thanks.

--
"love is
the search beneath one's spamguy **at** foxchange(.)com
tiny expectations"

[Michael Ash]

In article <BB2FCA95.A938%spamguy@ihate.spammers.com>,
Will Oram <spamguy@ihate.spammers.com> wrote:

> 'Object' in my code, in this case, happens to be an instantiated controller
> object. Shouldn't it receive instance, not class, methods then?

Object is also the name of a class in the frameworks. It's old, and kept
around mostly for compatability reasons, but it's there. Change the name
of your variable. Apparently the class's name takes precedence over your
variable's name.

The general convention is to make your class names begin with an
uppercase letter and make your variables begin with a lowercase letter.
If you do that you'll avoid this problem.

[John C. Randolph]

Mark Haase wrote:

>
> In article <BB2E1474.A908%spamguy@ihate.spammers.com>,
> Will Oram <spamguy@ihate.spammers.com> wrote:
>

> > I get a warning claiming it can't find the class (factory) method?** I was
> > unsure which object to use in 'Object''s place...I expected it to be the
> > object that contains the method's header and body. Instead, I get this
> > warning no matter *what* object I insert there.

>
> A factory method is a method that returns an a new instance of an
> object, but isn't a constructor. The Cocoa API has lots of these. Look
> at all the class methods for NSString (they are marked with +'s).

Close, but not quite.

In Obj-C parlance, a "factory" method is any class method. Not all
factory methods create instances. Methods that create objects are
+alloc, -copy, and what we refer to as "convenience methods", such as
+stringWithFormat: or -stringByAppendingString:.

-jcr