72 lines
1.7 KiB
Markdown
72 lines
1.7 KiB
Markdown
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# generate-function
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Module that helps you write generated functions in Node
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```
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npm install generate-function
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```
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[](http://travis-ci.org/mafintosh/generate-function)
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## Disclamer
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Writing code that generates code is hard.
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You should only use this if you really, really, really need this for performance reasons (like schema validators / parsers etc).
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## Usage
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``` js
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var genfun = require('generate-function')
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var addNumber = function(val) {
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var fn = genfun()
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('function add(n) {')
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('return n + %d', val) // supports format strings to insert values
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('}')
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return fn.toFunction() // will compile the function
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}
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var add2 = addNumber(2)
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console.log('1+2=', add2(1))
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console.log(add2.toString()) // prints the generated function
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```
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If you need to close over variables in your generated function pass them to `toFunction(scope)`
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``` js
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var multiply = function(a, b) {
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return a * b
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}
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var addAndMultiplyNumber = function(val) {
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var fn = genfun()
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('function(n) {')
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('if (typeof n !== "number") {') // ending a line with { will indent the source
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('throw new Error("argument should be a number")')
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('}')
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('var result = multiply(%d, n+%d)', val, val)
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('return result')
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('}')
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// use fn.toString() if you want to see the generated source
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return fn.toFunction({
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multiply: multiply
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})
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}
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var addAndMultiply2 = addAndMultiplyNumber(2)
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console.log('(3 + 2) * 2 =', addAndMultiply2(3))
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```
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## Related
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See [generate-object-property](https://github.com/mafintosh/generate-object-property) if you need to safely generate code that
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can be used to reference an object property
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## License
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MIT
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