The String Literal Returns

In the last entry, I celebrated what I felt was an elegant solution to the problem of the string literal in the context of overload function resolution. But it turns out there is another area in which the string literal proves problematic. Who would have thought such a foobar kind of entity could cause so much trouble? It's these kinds of ambushes that makes the extension of a language so unpredictable.  


So, here's the problem.


            throw "fritz";


what does the compiler do? it has to set everything up at compile-time, then it actually gets handled by a run-time library that makes use of a limited form of type reflection to figure the kind of object having been thrown.


there's no context, really. we don't know if the person is going to catch x, y, or z, so we can't know what to throw in any particular instance. this is all set up at compile-time.


Now, here is the rub:


          void f()


                     try { g(); }

                     catch ( String^ s ) {}

                     catch ( const char* pcs ) {}



            void g()


                     throw "fritz";



What gets caught? what an impossible question. one could argue if we are compiling for the CLR, then String^ should match, and if we are in native, and so on. But there's no reason to believe that just because we are compiling for the CLR, people are using String and not just const char*.


So, a string literal is thrown as a type const char*, not as String^.  My first reaction was, gosh, that's terrible. Then, I thought, what am I thinking? It seems a very small matter. It's not even something I would run into since I don't throw anything but class objects. I just add it for completeness.


I think if this bothers you, then you are bothered by our entire effort. Just as a sounding. That is, not everybody is happy with our work on C++/CLI. There are some folks out there that feel concern that we are somehow messing with their language, and we shouldn't be allowed to do that.


we aren't doing it that way at all. We have really wanted to be good c++ citizens while being excellent Microsoft employees. I have never felt any pressure to compromise either while I have been here. We have had an extraordinary degree of freedom not simply in our design, but in our being able to reach out and work with the general c++ community. this language is a coalition. I think we have all wanted to put the best face on C++ in what we regard as an otherwise hostile environment for C++. We think this is a win-win situation for everyone. if you don't like something, you should let us know. we're not a hundred thousand leagues removed from our users. if you want to use the language, you have every right to tell us what you think about it; how you find it; what you want. if you make a good case for it, I think it could be done. that's just my opinion. but I think we have an opportunity to together as a C++ community put forth C++ in an otherwise hostile environment that for some unbelievable reason thinks C# or Java comes anywhere near being as good a language. I don't understand it. It's not a question of knocking those languages. They took so much from C++ -- it's not hard, after all the hard stuff was worked out, to go back and clean it up. sure. C++ is messy. it was real hard to do. it was getting done while we were using it. we didn't know where it was going. Bjarne was implementing it, using it, it became the tool we all used to make our living. we wanted it to be the best possible language for programmers. at least I did. I don't have a philosophy. I don't make standards. I just program and write. and I do that best in C++. C# and Java mean nothing to me. Now I have my own language to use on .NET. That was my personal agenda in all this. I think you should check it out.


it was a great adventure. I find C++/CLI is something interesting again about C++ for me anyway. I'm not a fan of standards. I've never finally been involved in one. It's making a language that interests me, not in clean-up and all that necessary stuff for real-world production. I don't have the head for that.


so, I just wanted to make a personal statement. I have watched the team here for almost 3 years. I worked with them sometimes. I snarled at them sometimes. I was fed up with them once or twice. and yet they have produced something really wonderful in my opinion, and it is much better than I had dared imagine. I just love it. I can't wait to program with it – I'd like to drop everything and just start. this is exactly what I have been waiting for. to have a language to program .net. we didn't have one before.


C++/CLI is a entry visa nto what I call 3-dimensional programming. The CLR gives you the run-time as an entity to query, to modify, to almost in a sense be alive in. everything in a native program has to be done at compile-time. that is way too early for me to know exactly what needs to be done in many interesting environments. can't I wait? I'm not that performance critical that I need the machine.


my first analogy was going to be between the traditional Disney animation and the Pixar CGI, but I think a better analogy is between an instinct and a decision. that is, an instinct is the trigger of a built-in behavior that is insulated from and unaffected by the environment. a decision considers the environment (context) and memory (past behavior) in order to choose a best action. this is what is missing from native static programming. it really can't be smart enough for the kinds of problems we need to solve now in my estimate. I can't prove that.


I gave a talk at Disney Feature Animation a few months ago about C++/CLI, and a friend of mine who I love dearly, asked me, what do I need that for? he is in charge of plug-in 3D tools for Maya, a modeling toolkit for computer graphics. And he is right. But we need it I believe as a community going forward. and in that sense, we have opened that doorway for the C++ programmer. The worst case scenario was that the price of admission to this world was to have to renounce C++ -- I mean, mea culpa. we're such savages – we worry about performance, we break the type system, we make use of the underlying machine, we don't follow enough rules. we're loose cannons. Can't have loose cannons. I personally didn't want to accept that as being a true statement.


But you cannot argue something like that. I can't say, hypothetically, C++ can be as good a language under .NET as Java or C#. Nobody would hear that – they would just see Lippman being defensive, or delusional. you have to demonstrate it. That's the only way to really convince people. That's the only way I can ever convince myself in fact. So, that is what C++/CLI means to me.


I know Bjarne has his reservations and dislikes. Well, so do we all, if truth be told. But it's still just so wonderful overall. who cares if it's not perfect. I don't – I haven't gotten anything perfect, trust me. i don't know if it is better than this or that or the next thing. but it's really pretty good and i'm going to use it. and we really did it as a team.