Understanding interface() syntax

[gmluqa]

Hello,

I am going through the FundMe hardhat lesson. I am having difficulty wrapping my head around 2 aspects in the FundMe.sol contract.

AggregatorV3Interface public priceFeed;

and

constructor(address priceFeedAddress) {
        i_owner = msg.sender;
        priceFeed = AggregatorV3Interface(priceFeedAddress);
    }

Breaking down step by step as to how I understand it, constructor receives address 0xexample and puts it in priceFeed = AggregatorV3Interface(0xexample).
Why does it pass it through syntactically as AggregatorV3Interface(priceFeedAddress); when this is the typical syntax for adding constructor elements into an object? I checked the imported AggV3Interface.sol but could not find any constructor function that made this make sense to me.
The question boils down to, why this syntax: AggregatorV3Interface(priceFeedAddress); and not just, for example AggregatorV3Interface priceFeedAddress?

Thank you.

[alwayscommit]

I had to read a little bit about this, I could be wrong. @PatrickAlphaC should confirm!

This syntax basically means that the "address" that holds the concrete implementation of how a price is computed resides on the blockchain. We cast that address into this interface so that it's easier for us programmers to invoke functions at that address, those functions become available to us through this interface, and the address is where the concrete implementation lives. Also, I think this interface information would be added to our contracts ABI and allow the EVM to invoke appropriate calls. It's an interfacing mechanism.

These links might help
https://ethereum.stackexchange.com/questions/114502/how-do-interfaces-in-solidity-know-which-contract-they-are-interfacing
https://medium.com/coinmonks/solidity-tutorial-all-about-interfaces-f547d2869499

[gmluqa]

Thank you for the clarification, ease of targeting the specific address makes sense.

I must also add that it was revealed to me by @Initrodecoder (huge thanks as well) on GitHub that interfaces can take in ANY params without necesarrily needing to have a constructor in their code. This was a huge revelation for me because I assumed that an interface needed a constructor in order to take in params.

[ManuWeb3]

Faced the same dilemma at this point and your discussion helped me too to get my head wrapped around this ticklish concept.
Thanks to both of you.