50 lines
1.4 KiB
Solidity
50 lines
1.4 KiB
Solidity
pragma solidity ^0.4.24;
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/**
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* @title Initializable
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*
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* @dev Helper contract to support initializer functions. To use it, replace
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* the constructor with a function that has the `initializer` modifier.
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* WARNING: Unlike constructors, initializer functions must be manually
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* invoked. This applies both to deploying an Initializable contract, as well
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* as extending an Initializable contract via inheritance.
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* WARNING: When used with inheritance, manual care must be taken to not invoke
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* a parent initializer twice, because this is not dealt with automatically as
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* with constructors.
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*/
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contract Initializable {
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/**
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* @dev Indicates that the contract has been initialized.
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*/
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bool private initialized;
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/**
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* @dev Indicates that the contract is in the process of being initialized.
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*/
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bool private initializing;
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/**
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* @dev Modifier to use in the initializer function of a contract.
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*/
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modifier initializer() {
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require(initializing || isConstructor() || !initialized, "Contract instance has already been initialized");
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bool wasInitializing = initializing;
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initializing = true;
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initialized = true;
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_;
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initializing = wasInitializing;
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}
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/// @dev Returns true if and only if the function is running in the constructor
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function isConstructor() private view returns (bool) {
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uint cs;
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assembly { cs := extcodesize(address) }
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return cs == 0;
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}
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}
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