Const is the reverse. Constness is infectious down the stack (the callee of a const function must be const) while asyncness is infectious up the stack (the cal

Const is the reverse. Constness is infectious down the stack (the callee of a const function must be const) while asyncness is infectious up the stack (the caller of an async function must be async). So you can gradually add constness to subsections of a codebase while refactoring, only touching those local parts of the codebase. As opposed to async, where adding a single call to an async function requires you to touch all functions back up to main