No Operation On Same Value

Applying infix operations on the same value on both sides should be avoided.

Avoid/prefer

Expression to avoid | Preferred --------------------|---------- Expr and Expr | Expr Expr or Expr | Expr Expr xor Expr | false Expr == Expr | true Expr /= Expr | false Expr =< Expr | true Expr < Expr | false Expr >= Expr | true Expr > Expr | false Expr =:= Expr | true Expr =/= Expr | false Expr andalso Expr | Expr Expr orelse Expr | Expr Expr = Expr | Expr Expr -- Expr | []

Rationale

Using the same value on both sides of an infix operation (e.g., Expr == Expr, Expr - Expr, or Expr andalso Expr) results in outcomes that are constant or trivial by definition. These expressions are redundant and may indicate overlooked logic errors or placeholder code that was never revised. Removing or rewriting them improves code clarity and avoids misleading intent.

Options

• operations :: [atom()]
  • default:
    • 'and'
    • 'or'
    • 'xor'
    • '=='
    • '/='
    • '=<'
    • '<'
    • '>='
    • '>'
    • '=:='
    • '=/='
    • 'andalso'
    • 'orelse'
    • '='
    • '--'

Example configuration

{elvis_style, no_operation_on_same_value, #{
    operations => [
        'and',
        'or',
        'xor',
        '==',
        '/=',
        '=<',
        '<',
        '>=',
        '>',
        '=:=',
        '=/=',
        'andalso',
        'orelse',
        '=',
        '--'
    ]
}}