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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 | |
| 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 | |