Gareth Mensah

Good contracts are bits of code meant to facilitate, confirm, and implement an settlement between a number of events, permitting for transactions to occur with out the necessity for a 3rd occasion. Good Contract Patterns is a digest on the whole lot making these bits of code smarter.

Actual World Procedures

Procedures, one the various updates our builders have just lately launched, have been added to Scilla.

Should you’re aware of Scilla, Zilliqa’s good contract programming language, you already find out about transitions, that are the equal of object strategies in different languages. With the introduction of procedures we’re including a nifty piece of logic that ought to make your coding life simpler. Let’s first recap issues a bit.

transition foo (vname_1 : vtype_1, vname_2 : vtype_2, ...)

Transitions are outlined with the key phrase transition adopted by the parameters to be handed. They’re the general public interfaces of Scilla good contracts, by way of which customers (or different contracts) can modify the contract’s fields (i.e mutable states). When a transition is executed, its contract’s state is modified.

process foo (vname_1 : vtype_1, vname_2 : vtype_2, ...)

Procedures are outlined with the key phrase process adopted by the parameters to be handed. Just like transitions, they’ll modify the mutable states of a contract. Nevertheless, they differ in that they aren’t included within the contract’s public interface. In different phrases, procedures are like personal transitions that may solely be used throughout the scope of the contract, and as such can solely be invoked by the contract’s transitions and procedures (although it isn’t attainable for a process to be referred to as recursively).

First, by defining a process, that little bit of code might be reused by different transitions and procedures. Reusability makes for a extra constant, environment friendly and simpler to take care of codebase. Second, by figuring out bits of logic in a transition that may be decoupled makes for smaller transitions. Smaller transitions make for a code that’s simpler to learn and cause about. An instance of the usage of procedures might be discovered within the take a look at suite within the shogi_proc contract:

For the reason that contract is meant to close down as soon as the sport is over, the process Winner updates all of the fields which to make sure that nothing additional occurs within the contract. The process is named from two completely different locations — one when a participant resigns, and one when a King is taken by one other piece. With out a process, the code within the process physique must be duplicated, as is the case within the authentic Shogi contract.

By separating subroutines inside transitions and creating reusable bits of code, procedures make for smaller transitions, extra readable and reusable code.

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