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Introducing Transience, a library for safely using transient storage in Solidity (without assembly).

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Introducing Transience, a library for safely using transient storage in Solidity (without assembly).

https://github.com/ethereum-optimism/transience

What does the library offer?
- It allows writing and reading transient storage without assembly/Yul
- It prevents reentrant calls from overwriting transient storage

You get these methods:
- get(bytes32 _slot) for retrieving a transient value
- set(bytes32 _slot, uint256 _value) for setting a transient value

_slot and the current call depth are used to determine a unique location in transient storage.

Transience was developed for the interop contracts of the OP Stack/Optimism, specifically for CrossL2Inbox, where it's used for storing the identifier of a cross-chain message during its execution.

Transience was developed for the interop contracts of the OP Stack/Optimism, specifically for CrossL2Inbox, where it's used for storing the identifier of a cross-chain message during its execution.

https://github.com/ethereum-optimism/optimism/blob/3aeb6bdd3efe798713098f890359513eaaa91522/packages/contracts-bedrock/src/L2/CrossL2Inbox.sol

Check out the code!

h/t @philogy and @jtriley, whose libraries served as inspiration :)

Check out the code!

h/t @philogy and @jtriley, whose libraries served as inspiration :)

https://github.com/ethereum-optimism/transience

Use modifier 𝘳𝘦𝘦𝘯𝘵𝘳𝘢𝘯𝘵𝘈𝘸𝘢𝘳𝘦 to prevent a reentrant call from overwriting a slot in transient storage. This is possible because the modifier automatically increments and decrements the call depth when entering and exiting the function.