Ternary Put Operator in cpp possible?

Question

I was thinking about implementing a ternary put operator in cpp similar to "<<":

mystream <<< param2 param3;

Is this possible? Does it already exist? One remark: I remember having seen this:

out <<STDERR param

Wouldnt this already be a ternary operator?

score 2 · Accepted Answer · answered Jan 25 '13 at 14:47

To send C++ output to the stderr stream, use cerr << var1 << var2 or clog << 1 << 2.

There is exactly one ternary operator in C++, ?:, and it cannot be overloaded.

<<< is a binary operator in all languages where I've seen it. C++ does not have it; such a character sequence would be parsed as << < which is nonsense as neither can be used as a unary operator.

Finally, the second and third "operands" there are separated only by whitespace. C++ has no grammar productions including expression expression; that would lead to serious ambiguities.

The chaining behavior as in cerr << var1 << var2 is achieved by overloads of the form

std::ostream & operator << ( std::ostream &, my_class const & );

The ostream & return type allows the result of the first call cerr << var1 to be used as the left-hand operand to << var2.

Thanks, good answer too. I was looking to implement a manipulator that does not have to be separated by "<<" — B M, Jan 25 '13 at 14:56

score 1 · Answer 2 · answered Jan 25 '13 at 14:40

1

No, you can't make up new operators. You may only use the existing ones, and <<< is not among them.

out <<STDERR param

this can mean anything, both can be macros or literals.

answered Jan 25 '13 at 14:40

Luchian Grigore

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ok so the only way would be to overload "<<" to handle a struct or class that contains the "param1" and "param2"... Thanks! – B M Jan 25 '13 at 14:43
@BM yep, guess so. Or that's at least one of the options. – Luchian Grigore Jan 25 '13 at 14:45

Ternary Put Operator in cpp possible?

2 Answers2