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# 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
var genfun = require('generate-function')
var addNumber = function(val) {
var fn = genfun()
('function add(n) {')
('return n + %d', val) // supports format strings to insert values
('}')
return fn.toFunction() // will compile the function
}
var 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
var multiply = function(a, b) {
return a * b
}
var addAndMultiplyNumber = function(val) {
var fn = genfun()
('function(n) {')
('if (typeof n !== "number") {') // ending a line with { will indent the source
('throw new Error("argument should be a number")')
('}')
('var result = multiply(%d, n+%d)', val, val)
('return result')
('}')
// use fn.toString() if you want to see the generated source
return fn.toFunction({
multiply: multiply
})
}
var addAndMultiply2 = addAndMultiplyNumber(2)
console.log('(3 + 2) * 2 =', addAndMultiply2(3))
```
## Related
See [generate-object-property](https://github.com/mafintosh/generate-object-property) if you need to safely generate code that
can be used to reference an object property
## License
MIT
|
