90 lines
2.2 KiB
Markdown
90 lines
2.2 KiB
Markdown
# generate-function
|
|
|
|
Module that helps you write generated functions in Node
|
|
|
|
```
|
|
npm install generate-function
|
|
```
|
|
|
|
[](http://travis-ci.org/mafintosh/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
|