https://github.com/mafintosh/generate-function

Module that helps you write generated functions in Node
https://github.com/mafintosh/generate-function

Last synced: about 2 months ago
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Module that helps you write generated functions in Node

• Host: GitHub
• URL: https://github.com/mafintosh/generate-function
• Owner: mafintosh
• License: mit
• Created: 2014-07-30T17:18:56.000Z (about 10 years ago)
• Default Branch: master
• Last Pushed: 2020-05-02T20:53:57.000Z (over 4 years ago)
• Last Synced: 2024-04-14T04:08:29.659Z (5 months ago)
• Language: JavaScript
• Size: 14.6 KB
• Stars: 78
• Watchers: 4
• Forks: 9
• Open Issues: 2
• Metadata Files:
  • Readme: README.md
  • License: LICENSE

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README

        
# generate-function

Module that helps you write generated functions in Node

```

npm install generate-function

```

## Disclamer

Writing code that generates code is hard.

You should only use this if you really, really, really need this for performance reasons (like schema validators / parsers etc).

## Usage

``` js

const genfun = require('generate-function')

const { d } = genfun.formats

function addNumber (val) {

  const gen = genfun()

  gen(`

    function add (n) {

      return n + ${d(val)} // supports format strings to insert values

    }

  `)

  return gen.toFunction() // will compile the function

}

const add2 = addNumber(2)

console.log('1 + 2 =', add2(1))

console.log(add2.toString()) // prints the generated function

```

If you need to close over variables in your generated function pass them to `toFunction(scope)`

``` js

function multiply (a, b) {

  return a * b

}

function addAndMultiplyNumber (val) {

  const gen = genfun()

  

  gen(`

    function (n) {

      if (typeof n !== 'number') {

        throw new Error('argument should be a number')

      }

      const result = multiply(${d(val)}, n + ${d(val)})

      return result

    }

  `)

  // use gen.toString() if you want to see the generated source

  return gen.toFunction({multiply})

}

const addAndMultiply2 = addAndMultiplyNumber(2)

console.log(addAndMultiply2.toString())

console.log('(3 + 2) * 2 =', addAndMultiply2(3))

```

You can call `gen(src)` as many times as you want to append more source code to the function.

## Variables

If you need a unique safe identifier for the scope of the generated function call `str = gen.sym('friendlyName')`.

These are safe to use for variable names etc.

## Object properties

If you need to access an object property use the `str = gen.property('objectName', 'propertyName')`.

This returns `'objectName.propertyName'` if `propertyName` is safe to use as a variable. Otherwise

it returns `objectName[propertyNameAsString]`.

If you only pass `gen.property('propertyName')` it will only return the `propertyName` part safely

## License

MIT