Brilliant Julien! Thank you!
I had always been curious why initializers returned id, since their
return could be made specific to the class.
I've been doing what I've done in many classes, and some give me
grief, and not others.
Both of your assessments are correct.
To validate #1, if I change the offending line of code to do a cast:
xmppStream = [(XMPPStream*)[XMPPStream alloc] initWithDelegate:self];
the warning goes away. Of course, that's ugly and I won't retain that
code change because the deeper problem is exactly what you refer to
in item #2 -- I do have more than one class with the same initializer
signature. I'd thought the compiler would choose the right one
because I'd naively presumed that [className alloc] returned an
instance in that class, not an object of type id.
This is probably why I had to cast in my initializer:
- (XMPPStream*) initWithDelegate:(id)initialDelegate
{
self = (XMPPStream*)[super init];
If I change my initializer method name as you suggest so that it has
a unique signature,
- (XMPPStream*) initXMPPStreamWithDelegate:(id)initialDelegate;
and the creation of an instance accordingly:
xmppStream = [[XMPPStream alloc] initXMPPStreamWithDelegate:self];
all now compiles cleanly.
Now, the question is: is it bad to continue doing what I've been
doing in having the initializer interface defined to not return id
but an instance of the actual class? Or would my continuing to do
this merely be a non-conventional coding style?
--Stuart
On Mar 10, 2008, at 11:16 PM, Julien Jalon wrote:
1) All init methods should return (id) not a specific class
2) your initWithDelegate: is likely too generic as a name and its
signature conflicts with an other one.
Since [XMPPStream alloc] is typed id, the compiler might not be
sure of what method signature you want to use for -initWithDelegate:
In the second case, the compiler knows you are using -[XMPPStream
initWithDelegate:]
I tend to remember that the compiler warning was more specific
before Leopard, maybe a regression.
Nonetheless, good coding style should lead you to rename your
method to:
- (id)initXMPPStreamWithDelegate:(id)aDelegate;
instead of:
- (XMPPStream *)initWithDelegate:(id)aDelegate;
--
Julien
On Tue, Mar 11, 2008 at 9:19 AM, Stuart Malin
<[EMAIL PROTECTED]> wrote:
I have a line of code:
xmppStream = [[XMPPStream alloc] initWithDelegate:self];
That when compiled, receives a warning:
warning: assignment from distinct Objective-C type
Now, what's odd to me, is if I change the source code to this:
xmppStream = [XMPPStream alloc];
[xmppStream initWithDelegate:self];
It compiles without any warning.
The interface for the XMPPStream initializer is:
- (XMPPStream*) initWithDelegate:(id)initialDelegate;
And, in the file that is allocating and initializing, the xmppStream
variable is defined as:
XMPPStream *xmppStream;
So I don't see any reason that I should get the warning.
Any clues about why this happens would be appreciated.
I'm sure I must be overlooking something obvious...
This is happening with Xcode 2.4.1
[I have posted to both Cocoa and Xcode because I have no idea which
list would be better for this]
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