Problem calling class methods (Q:1)

Question

I'm trying to convert an old 'C' program containing some static methods into Obj-c but I'm having a few problems getting it to compile. In the header file I've got:

@interface Anneal : NSObject
...
...
+(float)approxInitT;
-(costType)simulatedAnnealing;
...

and in the implementation file, the two problem methods (also cut-down for brevity):

@implementation Anneal

+(float)approxInitT
{
    float T=0.0;
    int m2=0;

    ...

    if(m2==0)
        T = T_LIFESAVER;
    else
        T = T / m2 / log(initProb);
    return T;
}

-(costType)simulatedAnnealing
{
    float T;

    ...

    if(Tset)
        T=initialT;
    else
        T=[self approxInitT]; // error:incompatible types in assignment
}

Unfortunately I'm getting an "incompatible types in assignment" error even though 'T' and the return from the class method are both of type 'float'. While the code contains multiple source files (from which I'm expecting to hit a few more problems in the next few days), they're both in the same one. The problem is obviously caused by an error in the way I'm calling 'approxInitT()' but a search of the internet hasn't uncovered any answers to my prob so far.

As a novice I don't have any experience in multi-model code OR using static/class methods, and I'd sure appreciate any help with this. Thanks in advance :-)

Mahesh · Accepted Answer · 2011-02-18 11:25:41Z

2

Class methods donot belong to any particular instance of a class. So, try passing the message to class itself -

T = [ Anneal approxInitT ];

answered Feb 18, 2011 at 11:25

Mahesh

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2 Comments

Bender Over a year ago

Ahh, one more problem struck off the list! Thanks a lot Mahesh :-)

Mahesh Over a year ago

Not a problem. Good luck for the rest of the part.

Björn Marschollek · Accepted Answer · 2011-02-18 11:27:15Z

1

self references an instance of a particular class, but as you are calling a class method (+approxInitT), you must send the message to your class: T=[Anneal approxInitT]

answered Feb 18, 2011 at 11:27

Björn Marschollek

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