🚀 go-pugleaf

phalpern@truffle.ultranet.com (Pablo Halpern) writes:

>What I would like is some
>operation which tells me whether a type is a built-in type and/or a
>pointer type.

Try the following:

	template <class T>
	struct ext_type_info {
		enum { is_pointer = false };	// assume T is not a pointer...
	}

	// define a partial specialization
	template <class U>
	struct ext_type_info<U *> {		// ... unless it matches this
		enum { is_pointer = true };	// partial specialization
	}

	#include <assert.h>
	main() {
		assert(ext_type_info<int>::is_pointer == false);
		assert(ext_type_info<int*>::is_pointer == true);
	}

[This is now legal C++, but I don't know of any compilers that
support partial specialization yet.]

Also check out the numeric_limits class in the draft standard.
You can use `numeric_limits<T>::is_specialised' to determine
whether a type T is one of the fundamental numeric types.

[Similarly, numeric_limits<T> is not yet supported by most implementations.]

>  1) Is the format of the returned value of type_info::name() standard
>     enough for me to depend on it for this purpose?

No.

-- 
Fergus Henderson             |  #define x t=a[i],a[i]=a[m],a[m]=t/* use -O */
                             |  char a[]=" 12345678";main(m,i,j,t){for(i=m;i<
fjh@cs.mu.oz.au              |  9;x,i++)for(x,j=m;--j?(t=a[m-j]-a[m])-j&&t+j:
http://www.cs.mu.oz.au/~fjh  |  main(m+1)*0;);m-9||puts(a+1);} /* 8 queens */
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