Can anyone explain this syntax?

Ethereum Smart Contract Programming 201
#1

I saw this in some solidity code but don’t get what it is exactly:

(bool success, ) = msg.sender.call.value(amount)("");
require(success, "Transfer failed.");

what’s confusing me is the “(bool success, )” part.

It doesn’t look like the syntax of a variable and it doesn’t look like the syntax of a function. I get generally what it is being used FOR, but I don’t get why it is written that way or what you would even call this expression exactly.

1 Like
#2

Hey @CryptoEatsTheWorld sorry for the late answer, I missed this one :slight_smile:

You can ignore an ‘x’ number of returned values by using commas.

    function a() public view returns (uint,bool,uint) {
        return (3,false,3);
    }

    function b() public view {
        (uint number,,) = a();
    }

You can declare the variables that will hold the returned values between ().

    function b() public view{
        (uint number,bool boolValue,uint number2 ) = a();
    }

Let me know if you have questions,
Dani

#3

Interesting. So the parentheses on the left are catching the variables from the function on the right.

Is this called anything in particular? it’s just syntax I don’t see described anywhere.