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Comment by f00fc0d3 | Hacker News Reader

C99 is nice, but C still lacks generic. I am not talking about C++ template nonsense, but not having to write max element search for every primitive type.

I am working in DSP project which was started with typical C++ OO BS, finally with ended up with C compiled as C++ + some simple templates for cases as above.

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C has a generic: "void *". It just doesn't have any type safety.

It also has bad performance if you need to pass function pointers around.

Is this noticeably worse than calling through the vtable?

In C++ generics don't involve calling through a vtable.

C11 has type generic macros. You can build your own with the _Generic statement.

    int maxi(int, int);
    double: maxd(double, double);
    ...
    #define max(x) _Generic((x), int: maxi, double: maxd, ...default: maxi)

Yeah, but you still need to write those maxi, maxd :-(

I am not talking about C++ template nonsense, but not having to write max element search for every primitive type

How is it template 'nonsense', when those templates do exactly that?

Template metaprograming is nonsense, not simple type substitution. C++ templates are just too much, especially when mixed with substandard developers.

Using statement expressions and the typeof extension, you are able to write function-like, type-generic, scope-insensitive macros like this one:

    #define MAX(a,b) ({ \
        typeof (a) _a = (a); \
        typeof (b) _b = (b); \
        _a > _b ? _a : _b; \
    })

The inability to write template functions can be compensated by designing your function so that it takes a function pointer where the type-specific action occurs.

Typeof is not standard and many DSP compilers do not implement that. Secondly I meant max search in array, not between to scalar values which is trivial. I really don't want to have for(...) inlined everywhere.

Your MAX has no respect for namespaces or scopes. A real world macro is probably going to be called MYLIBRARY_MAX to avoid this. Secondly the C++ lambda solution is just easier to read.

    auto max = [](auto a, auto b) { 
        return (a > b) ? a : b;
    };

    max (3.1415, 42); // returns double
    max (42ul, 78u); // returns unsigned long
    max (17, 16); // returns int

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