SimpleStorage

[cluck135]

Hello! :)
Why is it that we have to write
simpleStorage = new SimpleStorage();
why not just leave it at
SimpleStorage public simpleStorage
What is the difference between the two?

The only thing I can think is that when you write it as SimpleStorage public simpleStorage it is simply an identifier of type for the variable? meaning I could pull data from the SimpleStorage Contract that is already defined and public. While when I do simpleStorage = new SimpleStorage() I can now write data into the new contract if there was a function that would change the state of some variable, and it would persist. Maybe I'm speaking nonsense though lol. I do have JS experience so this does feel similar to classes in JS.

`// SPDX-License-Identifier: MIT
pragma solidity ^0.8.0;

import "./SimpleStorage.sol";

contract StorageFactory {

SimpleStorage public simpleStorage;

function createSimpleStorageContract() public {
    simpleStorage = new SimpleStorage();
}

}`

[alymurtazamemon]

@cluck135

This line is called an instance of the contract.

SimpleStorage public simpleStorage;

it is similar to how we define variables in javascript

let simpleStorage;

And this line initializes it with SimpleStorage contract when we will press the createSimpleStorageContract button.

function createSimpleStorageContract() public {
    simpleStorage = new SimpleStorage();
}

similar to javascript

simpleStorage = //value according to data type.

Now come to your question why cannot we leave it as:

SimpleStorage public simpleStorage;

So the answer is, if we will not initialize it then we cannot interact with the SimpleStorage contract with the help of it.

hope it clears the question, please let me know if you have any queries.
Thank you

[cluck135]

Okay that helps a lot. One question why not use
uint256 public simpleStorage;
instead of
SimpleStorage public simpleStorage;
^ is this saying that simpleStorage is of type SimpleStorage?

Thanks for answering my question btw! :)

[alymurtazamemon]

yes, SimpleStorage is a type.

Mark it as answered if clears your query.