BuidlGuidl.eth
@buidlguidl
Building products, tools, and tutorials for the Ethereum ecosystem.
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Solidity error handling, by gas cost:
โข `require(cond, "msg")` โ ~50 gas per byte in the message string
โข `revert SomeError(arg)` โ ~22 gas per call + a 4-byte selector
Etherscan decodes named errors with their args. require strings are just opaque bytes in the revert data.
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Challenge 1: Crowdfunding.
The exercise:
โข Write a campaign contract with a goal and a deadline
โข Funders pay in, the contract holds ETH
โข On success: creator withdraws
โข On failure: funders get a refund
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Events vs state, rule of thumb:
โข Frontend needs to know it happened โ emit an event
โข Contract needs to act on it later โ write state
