A library version of the oraclize API, allowing for much lower deployment gas costs of contracts leveraging Oraclize.
Only use these libraries if you know what you are doing. They are considered experimental and not recommended for production use without a thorough audit.
Comparison of KrakenPriceTicker.sol deployment cost differences:
- Regular Unoptimized
1,867,173 gas
- with Library Unoptimized
733,111 gas
- Regular Optimized
1,429,716 gas
- with Library Optimized
712,380 gas
As these figures show, it can save up to 50-60% of a contract's deployment costs. It is important to note, that the library will be deployed separately, and its optimized deployment gas cost is almost 3M. It is still very useful in a singular contract basis, if you wish to keep all code within a single contract, as it will allow that singular contract to stay under the network's gas limit. Where the library really shines is in the case of modular architectures with multiple contracts dependant upon the Oraclize service.
Contract sources and associated computation archive can be found at: https://github.com/oraclize/ethereum-examples/tree/master/solidity/lib-experimental
Direct browser-solidity link to examples: https://dapps.oraclize.it/browser-solidity/#version=soljson-v0.4.11+commit.68ef5810.js&optimize=false&gist=ad3d1f6007942b727f5909b55e6445d2
NOTE: if the OffchainConcat.sol contract returns an empty string as the result, ensure the multihash can be retrieved from IPFS, and if not, you must run your own IPFS daemon, serving the archive.