Re: [liblo] Updating the example code for C++ programmers

On Mon, Jan 21, 2013 at 5:41 PM, Jeremia Bär <je...@je...> wrote:
> Hi,
>
> I looked at liblo for the first time today. I had some problems getting
> the example codes to run until I realized this is because of a subtle
> difference of C and C++. In 'example_server.c', line 82
>
> lo_arg_pp(types[i], argv[i]);
>
> (where types is of 'const char*') compiles nicely as C code using gcc.
> Using the same code from C++ however, compiling with g++, yields the
> following compiling error:
>
> examples/example_server.c: In function ‘int generic_handler(const char*,
> const char*, lo_arg**, int, void*, void*)’:
> examples/example_server.c:82:36: error: invalid conversion from ‘char’
> to ‘lo_type’
> examples/example_server.c:82:36: error: initializing argument 1 of ‘void
> lo_arg_pp(lo_type, void*)’
>
> Researching I found this: In C, an enum (e.g. lo_type) is always of type
> int. Thus, an implicit type-cast is performed. In C++, enum is a
> distinct type and implicit conversion is not allowed. Making the cast
> explicit makes the code work in both C and C++, like so:
>
> lo_arg_pp((lo_type) types[i], argv[i]);
>
> Now I see that this is an example C code and maybe even a C++ programmer
> should be aware of that difference. But it's quite nasty so I'd suggest
> changing the example code to the above line or add a comment for naive
> C++ programmers like I am ;-)

Hi,

Great suggestion.  I had to think about whether it was worth changing,
but I think you're right, it's a tiny change and could resolve some
confusion for newcomers.  Committed!


> I very much like liblo. It's very straightforward.

Glad to hear it!

I can tell you that there are in fact some shiny new C++ bindings
coming down the line ;)

Steve