Design Patterns¶

All patterns in this document are still in development and should only be used under own responsibility.

Behavioral Patterns¶

Guard Check: Ensure that the behavior of a smart contract and its input parameters are as expected.
State Machine: Enable a contract to go through different stages with different corresponding functionality exposed.
Randomness: Generate a random number of a predefined interval in the deterministic environment of a blockchain.

Access Restriction: Restrict the access to contract functionality according to suitable criteria. Checks Effects Interactions: Reduce the attack surface for malicious contracts trying to hijack control flow after an external call.
Secure VET Transfer: Secure transfer of VET from a contract to another address.
Pull over Push: Shift the risk associated with transferring VET to the user.
Emergency Stop: Add an option to disable critical contract functionality in case of an emergency.

Proxy Delegate: Introduce the possibility to upgrade smart contracts without breaking any dependencies.
External Storage: Keep contract storage after a smart contract upgrade.

String Equality Comparison: Check for the equality of two provided strings in a way that minimizes average gas consumption for a large number of different inputs.
Tight Variable Packing: Optimize gas consumption when storing or loading statically-sized variables.
Memory Array Building: Aggregate and retrieve data from contract storage in a gas efficient way.