Bizzare method signature, with unnamed arguments (obj-c)

Question

I wasn't aware this syntax was valid.

+ (void) methodName:(TypeObject *)typeObject1:(TypeObject *)typeObject2;

Which is then called like so:

[object methodName:obj1:obj2];

I find it ugly and disturbing, but it builds.

Can someone point me at a reference which explains why this is valid.

FWIW the codebase (inherited) that this comes from, is rife with sloppy, lazy stuff, dozens of spelling errors and looks like it was formatted by someone with no need to ever read it again. (Thank you again uncrustify.)

vikingosegundo · Accepted Answer · 2014-04-09T23:14:20.627

8

This is a well-kown and documented feature (pdf, p. 14)

In principle, a Rectangle class could instead implement a setOrigin:: method with no label for the second parameter, which would be invoked as follows:

[myRectangle setOrigin:30.0 :50.0]; // This is a bad example of multiple parameters

but apple discourage everbody of using parameter passing without keyword:

Use keywords before all arguments.
- (void)sendAction:(SEL)aSelector to:(id)anObject forAllCells:(BOOL)flag; -> Right.
- (void)sendAction:(SEL)aSelector :(id)anObject :(BOOL)flag; -> Wrong.

Why it was allowed by the creators of objective-C, I dont know. Maybe it has to do with the Smalltalk heritage.

edited Apr 09 '14 at 23:14

answered Nov 21 '12 at 01:46

vikingosegundo

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I guess I must've missed a meeting, I suppose Apple's discouragement has led to me not coming across it before. – ocodo Nov 21 '12 at 03:14
Maybe apple should teach the static analyzer to yield an warning — as unnamed parameters undermine one of objc strongest features. – vikingosegundo Nov 21 '12 at 03:21
@vikingosegundo Fix the link! – CrimsonChris Apr 09 '14 at 21:48
@CrimsonChris: what am I suppose to answer? Ay, Sir!? – vikingosegundo Apr 09 '14 at 22:57
1

@CrimsonChris: ok, I changed it. But consider to include "Please" or "may I ask you" in your next request. – vikingosegundo Apr 09 '14 at 23:15

Bizzare method signature, with unnamed arguments (obj-c)

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