What is the main difference between WriteSet, TransferSet and ContractResult in Ride4dApps?

Question

In Ride4dApps, the callable function returns WriteSet, TransferSet or a ContractResult but I still do not get the main difference between them? and who pays fees for this kind of dApps?

Answer 1

• TransferSet, It's a keyValue list which defines what outgoing payments will be made upon your contract invocation.
• WriteSet, It's a keyValue list which defines what data will be stored in contract's account upon your contract invocation(for example the caller address and balance). So basically it's a list of data entries that should be recorded to read the dApp state.
• ContractResult, It's the combination of WriteSet and TransferSet.

The sender pays fees in WAVES(1 + 4*(the cost of each script involved)) to the miner of the invocation.

Example:

ContractResult(
             WriteSet([DataEntry(currentKey, amount)]),
             TransferSet([ContractTransfer(i.caller, amount, unit)])
            )

Where:

• DataEntry (key : String, value : String | Binary | Integer | Boolean).
• i.caller is the caller address.