C++ operator overloading question

(3 posts)

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geek
guest
Posted 1 year ago #

Why certain operators can not be overloaded?
appapurapu
Member
Posted 1 year ago #

Never overload &&, ||, or , .
Reason:
Because short circuit semantics(it evaluates its arguments in left-to-right order) will replace with function call semantics.
For example, if you overload &&, then the
if( exp1 && exp2) looks like below
Case1: When operator&& is a member function ==> if(exp1.operator&&(exp2))
Case2: When operator&& is a global function ==> if(operator&&(exp1, exp2))
First, When function call is made, all parameters must be evaluated. ==> no short circuit.
Second, The language specification leaves undefined the order of evaluation of parameters to a function call, so there is no way to know whether exp1 or exp2 will be evaluated first.

As a result, never overload &&, ||, . operators.
Misraji
Member
Posted 1 year ago #

I think the question refers to the operators: Scope operator (::), Access Operator (.), Ternary Operator(? :) and (.*).
These are the ones that cannot be overloaded as opposed to should not be overloaded.

But the above answer is a nice one too. Thanks

~Ashish

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