Structfield

Find struct literals using non-labeled fields.

The structfield analysis reports the usage of struct literal using non-labeled fields more than defined limit (default: 2). The non-labeled field above the limit considered has higher cognitive load (harder to understand and rememeber).

Understanding Struct Literal

Given code, variable assigned using struct literal:

acc := Account{
    "[email protected]",
    "John Smith",
    []Permission{
        Permission{"account", "read"},
        Permission{"account", "write"},
    },
    true,
    false,
}

Above code is harder to understand, hard to guess the field name since we have to remember exact order of the fields. The workaround is you have to always look the declaration of the Account type.

Suggestion is to refactor the code to:

acc := Account{
    Email: "[email protected]",
    Name: "John Smith",
    Permission: []Permission{
        Permission{"account", "read"}, // Non-labeled here is still ok
        Permission{"account", "write"},
    },
    Verified: true,
    Deactivated: false,
}

The limit set to 2, which considered easy to understand and remember.

Benefits

By using the labeled fields you several benefits

  1. The fields doesn't have to be in order
  2. You don't have to declare the value if it's a default value

Example:

acc := Account{
    Email: "[email protected]",
    Name: "John Smith",
    Permission: []Permission{
        Permission{"account", "read"}, // Non-labeled here is still ok
        Permission{"account", "write"},
    },
    Verified: true,
    Deactivated: false,
}

can be simplified into:

acc := Account{
    Name: "John Smith", // `Name` come first
    Email: "[email protected]",
    Permission: []Permission{
        Permission{"account", "read"}, // Non-labeled here is still ok
        Permission{"account", "write"},
    },
    Verified: true,
    // Remove the `Deactivated: false` since it use default value
}

Installation

$ go install github.com/uudashr/structfield/cmd/[email protected]

or

$ go get github.com/uudashr/structfield/cmd/structfield

Usage

$ structfield -limit 2 testdata/src/a/*.go
testdata/src/a/a.go:20:9: Found 4 non-labeled fields on struct literal (> 2)

GitHub

https://github.com/uudashr/structfield