How much gas do we use for each transaction when we call a contract function ? --> depens on the lenght of code
Why can't we have more than 7 params in a function ? --> it's a solidity restriction
Why it return transaction: out of gas ?
How do I access solidity code from a contract address ? (see example with EOS)
In solidity we can't return an array, only tuples Right now, we can only return tuples string and number
to optimize its better to break up the require into individual to avoid user spendgin too much gas. For example notes params will go first because it's likely to have more than 50 characters than email or name.
using require consume less gas than if
everytime we migrate truffle it does create a new contract on the blockchain
when declaring variable, it's better to group variable by type to save gas : string first, then uint...
Are we using mapping because if we use array it's less efficient ?
You can't return a struct
memory vs storage storage does update variable/state memory does read state ---> you use it for mapping and struct
what are the solution if you update a contract ? You create a new one, copy all the data from the previous one. But how do you update the address for users ? --> For example, you can have a state of the contract to know if it's active or not Can you have specific address (admin) who call specific function ? --> Yes, you can have function who could be invoked by the creator of the contract for example
You can use PGG to encrypt the data on the blockchain if you don't want to have sensitive data on blockchain
You can't have a fully decentralised application because the hosting of the interface will not be decentralised (yet). You have solution like IPFS but it will not store your html files.