Created
October 20, 2013 01:47
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Separating command and query(setter/getter) of an object, enforcing command invocation(in this case a validation function) when a setter is called, making the dependent variable 'private' by making the constructor a closure, and using the ECMA5 Object.preventExtensions to block any further (mutation?) on the instances created by the constructor(…
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| <!DOCTYPE html> | |
| <html> | |
| <head> | |
| <meta charset=utf-8 /> | |
| <title>JS Bin</title> | |
| </head> | |
| <body> | |
| </body> | |
| </html> |
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| /*var fields = { | |
| docRoot: { | |
| validator: validateDocRoot, | |
| defaultValue: '/somewhere' | |
| }, | |
| somethingElse: { | |
| validator: validateSomethingElse | |
| } | |
| }; | |
| // Query, because it is returning 'config' | |
| function configure(values) { | |
| var key, config = { }; | |
| for(key in fields) { | |
| if(typeof values[key] !== 'undefined') { | |
| fields[key].validator(values[key]); | |
| config[key] = values[key]; | |
| } else { | |
| config[key] = values[key].defaultValue; | |
| } | |
| } | |
| return config; | |
| } | |
| // Command, because it doesn't return anything | |
| function validateDocRoot(config) { | |
| var fs = require('fs'), | |
| stat; | |
| stat = fs.statSync(config.docRoot); | |
| if(!stat.isDirectory()) { | |
| throw { | |
| error: 'Path is not a directory' | |
| }; | |
| } | |
| } | |
| function validateSomethingElse(config) { | |
| } | |
| describe('configure tests', function() { | |
| it('sets the values correctly to the config obj', function(){ | |
| var config = configure({ docRoot: '/tmp', someVal: 'someVal' }); | |
| expect(config).not.toBeUndefined(); | |
| expect(config.someVal).toEqual('someVal'); | |
| expect(config.docRoot).toEqual('/tmp'); | |
| }); | |
| }); | |
| describe('validateDocRoot tests', function() { | |
| it('throws an error if docRoot is not a directory', function() { | |
| validateDocRoot({ docRoot: '/xxx' }); | |
| }); | |
| }); */ | |
| var Obj = (function() { | |
| return function() { | |
| var docRoot = '/somewhere'; | |
| this.validateDocRoot = function() { | |
| // validation logic, throw Error if not OK | |
| }; | |
| this.setDocRoot = function(value) { | |
| this.validateDocRoot(value); | |
| docRoot = value; | |
| }; | |
| this.getDocRoot = function() { | |
| return docRoot; | |
| }; | |
| Object.preventExtensions(this); | |
| }; | |
| }()); | |
| // Using the Obj constructor | |
| var myObject = new Obj(); | |
| myObject.setDocRoot('/my/tmp/path'); | |
| console.log(myObject.getDocRoot()); | |
| //Testing the Obj constructor | |
| describe('validate docRoot', function() { | |
| var config = new Obj(); | |
| it('throw if docRoot does not exist', function() { | |
| expect(config.validateDocRoot.bind(config, '/xxx')).toThrow(); | |
| }); | |
| it('not throw if docRoot exists', function() { | |
| expect(config.validateDocRoot.bind(config, '/correctPath')).not.toThrow(); | |
| }); | |
| }); |
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