murphy@photon.mpr.ca (Gail Murphy) (12/14/90)
Does Objective-C support operator overloading? Gail Murphy | Voice : (604) 293-5462 MPR Teltech Ltd. | Fax : (604) 293-5787 8999 Nelson Way, Burnaby, BC | E-Mail: murphy@mprgate.mpr.ca Canada, V5A 4B5 | mprgate.mpr.ca!murphy@uunet.uu.net
lerman@stpstn.UUCP (Ken Lerman) (12/19/90)
In article <1990Dec14.155211.6598@mprgate.mpr.ca> murphy@photon.mpr.ca writes:
->Does Objective-C support operator overloading?
->
->Gail Murphy | Voice : (604) 293-5462
->MPR Teltech Ltd. | Fax : (604) 293-5787
->8999 Nelson Way, Burnaby, BC | E-Mail: murphy@mprgate.mpr.ca
->Canada, V5A 4B5 | mprgate.mpr.ca!murphy@uunet.uu.net
Objective-C supports method overloading, but not operator (+, -,...)
overloading.
Kenzack@bosslog.UUCP (Zacharias Beckman) (12/22/90)
In article <1990Dec14.155211.6598@mprgate.mpr.ca> murphy@photon.mpr.ca writes: >Does Objective-C support operator overloading? > >Gail Murphy | Voice : (604) 293-5462 >MPR Teltech Ltd. | Fax : (604) 293-5787 >8999 Nelson Way, Burnaby, BC | E-Mail: murphy@mprgate.mpr.ca >Canada, V5A 4B5 | mprgate.mpr.ca!murphy@uunet.uu.net Nope; Objective-C is not capable of overloading per the definition of the word if you are coming from C++. I.e.: Overloading allows multiple functions with the same name to be defined provided their argument lists differ sufficiently for calls to be resolved. (ARM pp. 307). In other words, you can't overload a function, method or operator in Objective-C. It's unfortunate -- I really miss this capability, particularly in method overloading. -- Zacharias J. Beckman | God grant me Serenity to accept things I can't change, Lower Code Dweller | Courage to change those I can, Boss Logic Inc. | and Wisdom to know the difference. uunet!bosslog!zack | --- Sinead O'Conner.
zack@bosslog.UUCP (Zacharias Beckman) (12/22/90)
In article <5928@stpstn.UUCP> lerman@stpstn.UUCP (Ken Lerman) writes: >In article <1990Dec14.155211.6598@mprgate.mpr.ca> murphy@photon.mpr.ca writes: >->Does Objective-C support operator overloading? > >Objective-C supports method overloading, but not operator (+, -,...) >overloading. Eh? Not unless your using a better Objective-C compiler than I am! I hope you are -- then I can upgrade! Overloading is not the same as overriding; which is to say, the same method name in the same object with a different parameter list is overloading. Objective-C doesn't support that for methods, functions or operators. If I'm wrong, please let me know! -- Zacharias J. Beckman | God grant me Serenity to accept things I can't change, Lower Code Dweller | Courage to change those I can, Boss Logic Inc. | and Wisdom to know the difference. uunet!bosslog!zack | --- Sinead O'Conner.
lerman@stpstn.UUCP (Ken Lerman) (12/28/90)
In article <191@bosslog.UUCP> zack@bosslog.UUCP (Zacharias Beckman) writes: ->In article <1990Dec14.155211.6598@mprgate.mpr.ca> murphy@photon.mpr.ca writes: ->>Does Objective-C support operator overloading? ->> ->>Gail Murphy | Voice : (604) 293-5462 ->>MPR Teltech Ltd. | Fax : (604) 293-5787 ->>8999 Nelson Way, Burnaby, BC | E-Mail: murphy@mprgate.mpr.ca ->>Canada, V5A 4B5 | mprgate.mpr.ca!murphy@uunet.uu.net -> ->Nope; Objective-C is not capable of overloading per the definition of the word ->if you are coming from C++. I.e.: -> -> Overloading allows multiple functions with the same name to be defined -> provided their argument lists differ sufficiently for calls to be resolved. -> (ARM pp. 307). -> ->In other words, you can't overload a function, method or operator in ->Objective-C. It's unfortunate -- I really miss this capability, particularly ->in method overloading. -> ->-- ->Zacharias J. Beckman | God grant me Serenity to accept things I can't change, ->Lower Code Dweller | Courage to change those I can, ->Boss Logic Inc. | and Wisdom to know the difference. ->uunet!bosslog!zack | --- Sinead O'Conner. IMHO the polymorphism available through Objective-C qualifies as operator overloading. More specifically, two classes may have methods with the same name (actually, with the same selector). The user of the method may be oblivious to the fact that two such functions exist, and the proper function will be automatically called based on the receiver. In Objective-C, the proper method is executed based on the class of the receiver, rather than the type of the arguments, but from a functional point of view, the receiver is one of the arguments of the method. IMHO the quotation from the ARM is a description of what C++ provides rather than a definition of operator overloading. I'd be interested in hearing more details of what method overloading functionality is missing which lead Zacharias to write: "I really miss this capability, particularly in method overloading." As an old time Objective-C programmer, I might be able to offer some suggestions. As always, the preceding is my opinion, not necessarily that of Stepstone, and may the force be with you. Ken
lerman@stpstn.UUCP (Ken Lerman) (12/28/90)
In article <192@bosslog.UUCP> zack@bosslog.UUCP (Zacharias Beckman) writes: ->In article <5928@stpstn.UUCP> lerman@stpstn.UUCP (Ken Lerman) writes: ->>In article <1990Dec14.155211.6598@mprgate.mpr.ca> murphy@photon.mpr.ca writes: ->>->Does Objective-C support operator overloading? ->> ->>Objective-C supports method overloading, but not operator (+, -,...) ->>overloading. -> ->Eh? Not unless your using a better Objective-C compiler than I am! I hope ->you are -- then I can upgrade! Overloading is not the same as overriding; ->which is to say, the same method name in the same object with a different ->parameter list is overloading. Objective-C doesn't support that for methods, ->functions or operators. If I'm wrong, please let me know! -> ->-- ->Zacharias J. Beckman | God grant me Serenity to accept things I can't change, ->Lower Code Dweller | Courage to change those I can, ->Boss Logic Inc. | and Wisdom to know the difference. ->uunet!bosslog!zack | --- Sinead O'Conner. If I had read this response prior to the previous one I just responded too, my response would have been different. It appears that we differ in our definitions of what method overloading is. At this point, I hope we understand the differing definitions and will drop discussion of which is "right". Objective-C permits: Class A: - foo:aFoo Class B: - foo:aFoo or - foo:aBar In this case, the implementation is chosen dynamically by whether the receiver is an A or a B. I would call this method overloading; I believe Zacharias would not. Objective-C also permits: Class A: - foo:(int)a Class B: - foo:(double)b In this case, the implementation is chosen by whether the receiver is an A or a B. I would call this method overloading. I don't know whether Zack (pardon the familiarity) would. If the wrong argument type were supplied, Objective-C would generate an error. To do this, though, the Objective-C compiler would have to know whether the receiver is an A or a B. You can do this in your code by writing your declaration as: "A anObject;" or "B anObject;" as appropriate. As far as having a better Objective-C compiler than Zack has, I should hope so. The one I'm using hasn't been released yet. :-) (This functionality is in the language specification beginning with 4.0) If Zack will send me email, or phone me at (203)426-1875, I can find out about getting him an upgrade if necessary. I write this as an exercise in freedom of speech without permission from Stepstone. May the force be with me. Ken
zack@bosslog.UUCP (Zacharias Beckman) (01/02/91)
In article <5952@stpstn.UUCP> lerman@stpstn.UUCP (Ken Lerman) writes: >IMHO the polymorphism available through Objective-C qualifies as >operator overloading. Polymorphism is, at least in my vocabulary, different from operator overloading. In overloading, a single object's method (or a function) has more than one invocation. Operator overloading specifies that operators, such as +, -, >, <, =, etc., can be overloaded to provide a functionality that the programmer supplies. This is not polymorphism. Polymorphism is available in both C++ and Objective-C. My personal favorite is C++, as I do not agree with the very loose typing of Objective-C. I also feel that C++ is more powerful, offering a few features which are key to me: multiple inheritance, overloading, operator overloading, public/private/protected keywords, and others. I am also looking forward with great expectations to templates and exception handling. >I'd be interested in hearing more details of what method overloading >functionality is missing which lead Zacharias to write: "I really miss >this capability, particularly in method overloading." As an example, here is a very simple class to show the overloading available in C++ (keep in mind the definition above). class Point : public Shape { uint x; uint y; uint z; public: void set(int a = 0, int b = 0, int c = 0) { x = a; y = b; z = c; } void set(Singularity & s, int i = 0) { set(s.x(), s.y(), i); } void set(Point & p) { set(p.x(), p.y(), p.z()); } Point & operator=(Point & p) { if (p != this) set(p); } uint x() { return x; } uint y() { return y; } uint z() { return z; } }; You might want to actually have this class descend from a Singularity class which would represent a 2-d point. But, to keep things simple, I didn't do that. Obviously, the class doesn't do much. However, it does allow the following: Point myPoint; // declare a couple of Point objects Point anotherPoint; Singularity single; // a singularity (a 2-d point) anotherPoint.set(50, 50, 50); // set anotherPoint to [50,50,50] single.set(80, 80); // presumably set singularity to [80,80] myPoint.set(anotherPoint); // set myPoint to [50,50,50] myPoint.set(); // set myPoint to [0,0,0] myPoint.set(50, 100); // set myPoint to [50,100,0] myPoint.set(50, 100, 5); // set myPoint to [50,100,5] myPoint.set(single); // set myPoint to [80,80] myPoint.set(single, 5); // set myPoint to [80,80,5] myPoint = anotherPoint; // set myPoint back to [50,50,50] My point (pun partially intended) is that it is a tool which makes my life as a programmer a bit easier. This example also shows default arguments in action, which is also "missing" from Objective-C. What it comes down to is having an object Thing with the method set (in C++) or an object Thing with the methods setInt, setFloat, setOther, etc. (in Objective-C). C++ allows us to be truly "object-oriented" -- we send a set method, and don't worry about what the argument is. -- Zacharias J. Beckman | God grant me Serenity to accept things I can't change, Lower Code Dweller | Courage to change those I can, Boss Logic Inc. | and Wisdom to know the difference. zack@bosslogic.com | --- Sinead O'Conner.
cox@stpstn.UUCP (Brad Cox) (01/02/91)
In article <193@bosslog.UUCP> zack@bosslog.UUCP (Zacharias Beckman) writes: >Polymorphism is available in both C++ and >Objective-C. My personal favorite is C++, as I do not agree with the very >loose typing of Objective-C. This is not to start a flame war, just to point out that this is like saying 'Variables are supported in both C and shell. My personal favorite is C, as I do not agree with the very loose typing of that shell provides for connecting filters through pipes. There's a figure in my 'Planning the Software Industrial Revolution' article (November 1990 IEEE Software magazine) that proposes a vocabulary for discussing tools at diverse software architectural levels, with pipes/filters as a 'rack-level' modularity/binding technology, Fabrik/Metaphor lightweight processes as a 'card-level' technology, Smalltalk/Objective-C as a chip-level technology Ada, C, and C++ as gate- and block-level technologies. Unfortunately, the published figure contains a serious error in Objective-C's favor at the card-level integration level, that they've agreed to fix in the next issue. Just as tightly-coupled gate- and block-level technologies have a place in hardware engineering, but do not compete with loosely-coupled chip-, card-, and rack-level technologies, the same is true in software. Of course, without a mature vocabulary for making such distinctions, we waste energy with language wars. I have always believed that the Objective-C versus C++ debates have been driven more by misunderstanding than by appreciation for their differences. I've never viewed them as competitors, any more than shell and C are competitors. As a better C, C++ provides a better substrate on which to base new incarnations of Objective-C. -- Brad Cox; cox@stepstone.com; CI$ 71230,647; 203 426 1875 The Stepstone Corporation; 75 Glen Road; Sandy Hook CT 06482
glang@Autodesk.COM (Gary Lang) (01/06/91)
>IMHO the polymorphism available through Objective-C qualifies as >operator overloading. Oh come on. I'm as big a fan of OC as the next guy, but the fact that I can't build my own floating point package using my own function calls and then overload math operators so that the code looks like all the other math code in the world means that you really don't have _operator_ overloading (BTW this is an essential feature for some work I have in mind for a new platform that's coming out that you might want to support soon - email me for details). I agree with you; I don't miss the method overloading in C++ because of the way OC works. But don't overstate your case...you cannot overload the basic operator tokens of your language. On the other hand, OC on the NeXT under 2.0 is supposed to support C++ so presumably you can do this there (I haven't tried it yet because everything I'd meant to overload is done through method overloading as you describe, and I don't need it)... - g -- Gary T. Lang (415)332-2344 x2702 Autodesk, Inc. Sausalito, CA. MCI: 370-0730
glang@Autodesk.COM (Gary Lang) (01/06/91)
>I've never viewed them as competitors, any more than shell and C are
Well said.
- g
--
Gary T. Lang (415)332-2344 x2702
Autodesk, Inc.
Sausalito, CA.
MCI: 370-0730