solhint-community
non-state-vars-leading-underscore
Description
Variables that are not in contract state should start with underscore. Conversely, variables that can cause an SLOAD/SSTORE should NOT start with an underscore. This makes it evident which operations cause expensive storage access when hunting for gas optimizations
Options
This rule accepts an array of options:
| Index | Description | Default Value |
|---|---|---|
| 0 | Rule severity. Must be one of “error”, “warn”, “off”. | warn |
Example Config
{
"rules": {
"non-state-vars-leading-underscore": ["warn"]
}
}
Notes
- event & custom error parameters and struct memer names are ignored since they do not define variables
- this rule is contradictory with private-vars-leading-underscore, only one of them should be enabled at the same time.
Examples
👍 Examples of correct code for this rule
mutable variable should NOT start with underscore since they DO cause storage read/writes
pragma solidity 0.4.4;
contract A {
uint256 public foo;
}
immutable variable should start with underscore since they do not cause storage reads
pragma solidity 0.4.4;
contract A {
uint256 immutable public _FOO;
}
block variable with leading underscore
pragma solidity 0.4.4;
contract A {
function foo() public { uint _myVar; }
}
function parameter with leading underscore
pragma solidity 0.4.4;
contract A {
function foo( uint256 _foo ) public {}
}
👎 Examples of incorrect code for this rule
mutable variable starting with underscore
pragma solidity 0.4.4;
contract A {
uint256 public _foo;
}
block variable without leading underscore
pragma solidity 0.4.4;
contract A {
function foo() public { uint myVar; }
}
function parameter without leading underscore
pragma solidity 0.4.4;
contract A {
function foo( uint256 foo ) public {}
}
Version
This rule was introduced in Solhint 4.0.0-rc01