+ 2

Need for custom deleter

Hello I am using shared pointer. If it is for int or double, we don't need to worry as it is inbuilt type. For class , we may have resources like heap allocation or text file opening. This is done in constructor and destructor will free both these resources. Make shared also calls destructor. So I m not getting point of having custom deleter for shared pointer.. why custom deleter is required ? If I am not wrong , [] array of smart pointer was not releasing memory properly till C++ 17 but now it is also solved and calls delete [] instead of delete Having said this all , do we literally need custom deleter now a days ?

6th Oct 2021, 8:32 AM
Ketan Lalcheta
Ketan Lalcheta - avatar
2 Respostas
+ 3
>Volodymyr Melnychenko It seems that the first practicing software developer signed up for Sololearn, not a student who is just learning.
15th Oct 2021, 1:01 PM
Computer Engineer
Computer Engineer - avatar
+ 1
Class destructor and custom deleter both exist for different uses. I agree with you that in most cases the custom deleter concept seems superfluous and redundant, indeed, in my practice I rarely use it. Destructor is invoked always no matter where the class is used. Custom deleter on the other hand is invoked only to clean up a smart pointer and can be different in different parts of your code. While thinking about it I see two reasons to use custom deleters. First, you use it when the underlying class does not have a destructor at all, that's the case with plain C structures, for example. Second, when you need to do something more than just destruct the object, say you want to update other structures, send events or simply log for debug purposes.
15th Oct 2021, 12:54 PM
Volodymyr Melnychenko
Volodymyr Melnychenko - avatar