How does some applications working on smart contracts bring new upgrades

[sadath-12]

As i see smart contracts cannot be changed . But can someone please explain how do some companies websites running on a smart contract upgrade and bring their newer version ? they have the smart contract and in order to upgrade they need to change it and re deploy which will create another contract address right and hence the interactions happened with that applications will be vanished right with respect to data associated with previous contract ?

[othaime-en]

Hey @sadath-12 checkout this article by ethereum. It explains this scenario in an indepth manner more than I can.

[sadath-12]

thank you so much but what if rules are changed through upgrades how is it immutable then for users using the application with trust

[othaime-en]

It is important to note that when we talk about immutability, we talk about the state of the blockchain/smart-contract not it's upgradability (changing the logic). Upgrading smartcontracts involves tweaking the logic to improve it or fix any vulnerabilities. However, as you can see from the article i've shared, all forms of upgrading smartcontracts preserve the state of the blockchain or data contained in the smart contract. Also as you may note, since the code is already deployed into the blockchain, it also can't be changed. That's why the upgrading methodology involves somehow redirecting the users to the new smart contract.

[sadath-12]

oh got great explanation though !

[alymurtazamemon]

@sadath-12 You should watch the video from the timestamp: 28:53:11. Here Patrick explains everything and also the number of approaches for upgrading smart contracts.

[sadath-12]

Oh got it

[krakxn]

Your doubt is warranted, and yes, Patrick clarifies it (different ways to upgrade depending on the trustworthiness and complexity) later on in the course. Just hang on.