Can you please explain this concept and how it works?

Question

I would like to clear my doubt that when caller and called contract are same. Then the memory will get a new initialization right? or is it a different case.

Answer 1

You can call your own contract's external functions (recursively) by this.functionName. If you inspect msg.sender in that subsequent call, the result is the that contract's address. Since it's an external call, a new memory range is allocated.

Here's an example:

pragma solidity ^0.8.0;
contract A {
    event Addr(address);

    function myA() view external returns (address) {
        return msg.sender;
    }

    function test() public {
        emit Addr(this.myA());
    }
}

If you call the function test, you see it emits the same contract address.