I just read this post too and I was going to say the same thing! There are flags built in to stop you doing this sort of thing. I like -Wall -Werror -Wextra -pedantic off the top of my head, there are at least 5 that should be a requirement for any project, I have a standard line of about 10 flags that I apply to all of my projects.

http://gcc.gnu.org/onlinedocs/gcc/Warning-Options.html

@ everyone:

I know if you are in bussiness or games programming you might not have a choice but to use Visual Studio, but at least compile under gcc once in a while, even if you don’t release with it, just to make sure that you are creating robust code. At my work place we have 3 automatic regression/build test machines that every hour checks out a copy of our code and tries to build the Visual Studio project and gcc project for Windows as well as the gcc project for Linux and Mac and then email us if anything fails to build. The best thing is that each developer doesn’t need to actually have a Windows, Linux and Mac machine to write cross platform code, he quickly gets an idea via email of what will not compile. It would be great in the future to also have a commit hook so that you can’t even commit if the code is not cross platform.

$ cat test.cpp struct Vec3 { float i1,i2,i3; Vec3(float toto); };

Vec3 v = (2,3,0); tom@tomdell:~ $ g++ -c -Wall test.cpp test.cpp:6: warning: left-hand operand of comma has no effect test.cpp:6: warning: right-hand operand of comma has no effect

As for the comma operator, one use in Javascript :

function doStuffWithNode(node) { if (someInvalidCondition) return Warning(’invalid node’), null }

This would call the log code then return null. I really prefer that to opening up braces and using 4 lines to log then return.

Michael: I’m a bit disappointed the first flame I got on this blog was that weak. Ah, where are the good old days of comp.lang.c++ where people knew how to flame

And the most frustrating bit of C++ are not even the possibility of subtle errors – compile times are horrenduous. (Expect to see a few more articles on that)

In general: in case anybody thinks this is my only beef with C++ – it’s reason #947, as I said. It’s just the one thing that caused me to vent.

What about this super-common idiom:

for (int i = 0, size = v->size(); i < size; ++i)

?

(you might not want to use an iterator, perhaps because you want the index as well as the value…)

And my complaint isn’t that C++ doesn’t accomodate this. I’d be perfectly happy with a syntax error. My complaint is that by accidentally typing something that’s clearly not valid code, all the “magic” imbued in C++ generates working code that’s not even close to what I intended.

The main complaint: explicit constructors are safer than implicit ones – they should be the default. (Immediately followed by the comma operator)

Mark: See above – we’ve got plenty of PODs, so the initialization code is unfortunately a valid choice. (There are also plenty of constructors. But as long as I’d get an error if I picked the wrong one, I’d be happy)

Dumb: Always glad to see a well-reasoned argument.

If the latter case, then perhaps you waited too long to read the ARM. This is in an uncommon usage/style/attempt (in C++), I think.

No language that I’ve used accomodates every means of expression. Most (even C++) clobber you with a syntax error. Generally.

Yeah, you got bit here. Try to be nice.

A a = (x,y,z); // or B b = {x,y,z};

…in real code. The reason is that C++ have been ingrained with the idea that they cannot statically initialize classes using the assignment operator. You will always see that its done with some constructor. Part of the reason for this is that C has just piss-poor support for anything other than scalar values. For example, tuples and dictionaries just don’t exist in C. Even array’s are broken since you can’t in general do:

C c = {1,2,3};

for a real type C that you’ve defined. It has to be a struct with no constructors, like you noted in your post.

Fortunately, some people have heard our complaints and have made C++ marginally more useful. Look at the Boost assignment library for an example of why the comma operator is a good thing to have. Of course, any language that needs a library to help out with something as simple as assignment is probably pretty broken.