How Do State Variables Protect against Unexpected External Calls?
State variables protect against unexpected external calls primarily through the use of a "reentrancy guard" or a "lock" variable. This is a boolean state variable, initially set to false.
At the beginning of a critical function, the guard is set to true, and a check ensures it is not already true. At the end of the function, it is reset to false.
If an external call attempts to re-enter the function before the first execution completes, the check will fail, and the transaction will revert, effectively blocking the reentrancy.
Glossar
External Call
Interaction ⎊ This describes a smart contract's necessary communication with an entity outside its immediate execution environment, most commonly an oracle network to fetch real-world asset prices or event outcomes.
Reentrancy Guard
Mitigation ⎊ A Reentrancy Guard functions as a critical control mechanism within smart contracts, specifically designed to prevent recursive calls to the same function before the initial execution completes.
State Variables
Mechanism ⎊ State variables, within cryptocurrency and financial derivatives, represent the core inputs defining a system’s present condition, crucial for modeling price dynamics and risk assessment.
External Calls
Call ⎊ External calls, within cryptocurrency derivatives and options trading, represent off-exchange communications impacting price discovery and order flow.