Writing good software has never been an easy task, however the introduction of common design patterns by the gang of four (Gamma, Helm, Johnson, Vlissides) in their seminal book 'Design Patterns' in 1995, went a long way to creating a language of patterns, an essential method of describing solutions to common problems.

This is a library of smart-contract patterns written in Solidity. Writing smart-contracts has been proven to be difficult, exemplified by TheDAO in recent events. It is my intention that this repository will serve the community by collating the most useful smart-contract patterns for public benefit.

The patterns are logically divided into four groupings. Lifetime is a group of patterns that control the construction and destruction of smart-contracts. Maintenance is a group of patterns that provide mechanisms for live contracts. Ownership is a group of patterns that control access to smart-contract. And finally Security is a group of patterns that seek to mitigate security related matters.

auto_deprecation - Provides a mechanism for automatic expiration of a contract interface after some period of time has elapsed. lifetime/auto_deprecation.sol

mortal - Provides a method for the creator of a contract to destroy it. lifetime/mortal.sol

relay - Provides a method for the creator of a contract to update it to a newer version without invalidating the address. maintenance/relay.sol

data_segregation - Segregates a contract and its data so as to avoid costly data migrations. maintenance/data_segregation.sol

owner - Limits access to certain functions to only the owner of the contract. ownership/owner.sol

circuit_breaker - The circuit breaker pattern allows the owner to disable or enable a contract by a runtime toggle. security/circuit_breaker.sol

rejector - The rejector pattern automatically rejects all ether sent to it. security/rejector.sol

speed_bump - The speed bump pattern limits how often a function can be called to deliberately slow down certain functions. security/speed_bump.sol

Contributions are welcome. Please use the issue tracker to submit requests or report issues.

If you would like to submit a pattern to the library, please first submit a proposal via the issue tracker.

The code contained within this repository is licensed and distributed under the Apache 2.0 license. It is my intention to invite derivative works, as well as encourage commercial use without obligation.

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