问题
I'm trying to enforce a const 'getter' method of a class to be called upon only lvalue instances of the class, via a ref-qualifier and for some reason getting an unexpected result (I'm compiling with clang 6.0.1 with C++ 17 support, via c++1z flag, on Windows):
The declaration bool getVal() const &; allows the method to be called on rvalue references also.
The declaration bool getVal() &;
doesn't allow the method to be called on rvalue references BUT, as I understand - the function isn't a const method no more, which is problematic, design-wise, for a 'getter' method.
What's the right way to get both characteristics for a method?
回答1:
Use bool getVal() const &;, but add a deleted overload for rvalues:
bool getVal() const && = delete;
来源：https://stackoverflow.com/questions/62609367/c-const-member-func-that-can-be-called-upon-lvalue-instances-only-using-a