farm-plugin-overload

Compile-time function overloading for FarmFE — implement runtime overloading via @overload decorator with i18n error messages.

Install

npm install farm-plugin-overload

Concept

JavaScript/TypeScript supports overloading in declarations but not in implementations. This plugin bridges that gap: mark multiple functions with @overload('name') and the compiler generates a single dispatcher that selects the right implementation based on argument count and types.

Usage

import overload from 'farm-plugin-overload'

export default {
  plugins: [overload()],
}

Example

@overload('greet')
function greet_0(): string { return 'Hello!' }

@overload('greet')
function greet_1(name: string): string { return `Hello, ${name}` }

@overload('greet')
function greet_2(name: string, age: number): string { return `Hello, ${name}, age ${age}` }

// Call the unified name — dispatcher selects the right implementation
greet()              // → 'Hello!'
greet('Alice')       // → 'Hello, Alice'
greet('Alice', 30)   // → 'Hello, Alice, age 30'
greet(true)          // → Error: No overload for "greet" matches (boolean)

Compiles to:

function greet_0() { return 'Hello!' }
function greet_1(name) { return `Hello, ${name}` }
function greet_2(name, age) { return `Hello, ${name}, age ${age}` }

function greet(...args) {
  if (args.length === 0) return greet_0(...args)
  if (args.length === 1 && typeof args[0] === "string") return greet_1(...args)
  if (args.length === 2 && typeof args[0] === "string" && typeof args[1] === "number") return greet_2(...args)
  throw new Error(`No overload for function "greet" matches the provided arguments (${args.map(a => typeof a).join(", ")}).`)
}

.d.ts Generation

The plugin generates TypeScript declaration files with proper overload signatures, so IDEs show correct type hints:

declare function greet(): string;
declare function greet(name: string): string;
declare function greet(name: string, age: number): string;

i18n Error Messages

Runtime errors support multiple locales:

| Locale | Code | Example | |--------|------|---------| | English | en | No overload for function "greet" matches the provided arguments (boolean). | | 中文 | zh | 函数 "greet" 没有匹配参数 (boolean) 的重载。 | | Latina | la | Nulla supersonicatio pro functione "greet" congrit argumentis (boolean). |

overload({ locale: 'zh' })  // Chinese error messages

Options

• locale — Error message locale. Default: 'en'. Supported: 'en', 'zh', 'la'
• extensions — File extensions to process. Default: ['.ts', '.tsx', '.js', '.jsx']

License

MIT