How to create Support function for internal Class use

Question

I have created a class to find the MoonRise and Set time. There is a java code available and I am translating it to Obj-C.
My problem is that for the calculation there are many support functions which is internally used. When I try to duplicate this as follows
-(double) frac:(double)x {
// returns the fractional part of x as used in minimoon and minisun
double a;
a = x - floor(x);
if (a < 0) a += 1;
return a;
-(void)minimoon:(double)t {
// takes t and returns the geocentric ra and dec in an array mooneq
// claimed good to 5' (angle) in ra and 1' in dec
// tallies with another approximate method and with ICE for a couple of dates
double L0, L, LS, F, D, H, S, N, DL, CB, L_moon, B_moon, V, W, X, Y, Z, RHO;
//var mooneq = new Array;
L0 = frac(0.606433 + 1336.855225 * t); // mean longitude of moon
At this point it gives an error implicit declaration of function frac,
My question is how to create such helper functions which are used internally, actually there are many such functions where functionA call B which calls C.
Thanks
Raj

Answer 1

Here's yet another approach (creating a private category):
@interface MYClass (Private)
- (double)frac:(double)x;
@end
@implementation MYClass
- (void)minimoon:(double)t {
// takes t and returns the geocentric ra and dec in an array mooneq
// claimed good to 5' (angle) in ra and 1' in dec
// tallies with another approximate method and with ICE for a couple of dates
double L0, L, LS, F, D, H, S, N, DL, CB, L_moon, B_moon, V, W, X, Y, Z, RHO;
//var mooneq = new Array;
L0 = [self frac:(0.606433 + 1336.855225 * t)]; // mean longitude of moon
- (double)frac:(double)x
// returns the fractional part of x as used in minimoon and minisun
double a;
a = x - floor(x);
if (a < 0) a += 1;
return a;
@end
<div class="jive-quote">rajkhand wrote:
I liked the first method as I don't have to change much of the java code.
I like it too. I use that very regularly (though I often use C++/Objective C++), since there is typically a lot of implementation in any class that does not need to be an ObjC instance method. This approach helps to reduce the object's interface to its essentials while keeping maintenance low.
I'll put all the helper functions above the implementation.
Is there a good book/web site where I can get such insight? I know C and Delphi/pascal
Well, Objective-C is a superset of C. If you're porting Java, you'll find protocols (ObjC) similar to interfaces (Java).
*Getting Started*
Apple's version of ObjC is different from others. For the language, Apple's docs are the standard (IMO):
Language:
http://developer.apple.com/documentation/Cocoa/Conceptual/ObjectiveC/ObjC.pdf
If you are comfortable with C, this guide will help learning Objective-C quickly, though it has not been updated for (Apple's) Objective-C 2.0:
http://www.amazon.com/Objective-C-Pocket-Reference-Andrew-Duncan/dp/0596004230/r ef=sr14?ie=UTF8&s=books&qid=1245404236&sr=8-4
There are a few books on the ObjC2 language, but I have not read them (I just read Apple's docs for this).
OOP/Design:
http://developer.apple.com/documentation/Cocoa/Conceptual/OOPObjC/OOPObjC.pdf
Research
Good site for archives of tips, tricks, and even some hacks:
http://www.cocoadev.com/
Apple's lists (Cocoa, Xcode, ObjC, and specific technologies):
http://lists.apple.com/mailman/listinfo
This one sees the most traffic for Cocoa, and ObjC topics :
http://lists.apple.com/mailman/listinfo/cocoa-dev
Online archive for aforementioned Xcode and Cocoa list submissions:
http://www.cocoabuilder.com/
There are a lot of good sites/blogs out there as well.
Questions
Apple's lists (linked above) will typically yield good answers in a short time, you can also try here.
Thanks a million
Raj
You're Welcome,
J