Generic object class construction

objectify.js

/**
 * GenericObject / objectify.js
 *
 * Creating new objects with neat setters and getters over again is annoying, so let's automate it.
 *
 * @author Alexander Schulz ([email protected])
 */

var Objectify = (function () {
    "use strict";

    var objectify = function objectify(config) {
        if (typeof config !== "object") {
            throw new SyntaxError("Missing object config");
        }
        if (!("_this" in config && "name" in config._this)) {
            throw new SyntaxError("An object name is required");
        }

        var name = config._this.name;
        var genericBody = "{\n" +
                          "    var constructor = Object.getPrototypeOf(this);\n" +
                          "    Object.defineProperties(this, {\n" +
                          "        name: { value: name },\n" +
                          "        displayName: { value: name },\n" +
                          "        __props__: { value: config }\n" +
                          "    });\n" +
                          "\n" +
                          "    return constructor.call(this, staticStorage, obj);\n" +
                          "}";

        // staticStorage needs to be declared and ""bound"" in this context to actually be static in between instances
        // The Function constructor is used to set the name, setting the name and displayName property may not work everywhere sadly
        var generic = (new Function("staticStorage", "name", "config", "return function " + name + "(obj) " + genericBody))({}, name, config);
        // If the length doesn't match then that means someone tried to inject a different function through the name variable!
        if (generic.toString().length !== 15 + name.length + genericBody.length) {
            throw new Error("Constructor didn't match expected length");
        }

        Object.defineProperty(generic, "prototype", {
            value: GenericObject,
            writable: false,
            configurable: false,
            enumerable: false
        });

        return generic;
    };

    var GenericObject = function GenericObject(staticStorage, obj) {
        if (typeof this.constructor === "undefined" || (this.constructor.name || "window").toLowerCase() === "window" || this.constructor === Object) {
            throw new TypeError("Must be called with 'new'");
        }

        var self = this;
        // Contains all the meta information about this object
        var _properties = this.__props__ || { _this: {} };
        // Actual value storage for all "normal" values
        var _privateStorage = {};
        // Value storage for all static values shared between instances
        var _staticStorage = staticStorage || {};
        // Pseudo-object with getters and setters for easier accessing
        var _values = {};

        var _valid = typeof obj === _properties._this.type;
        var _invalidAt = null;

        var isType = function (val, type) {
            return typeof type === "string" ? typeof val === type : val instanceof type;
        };
        var typeName = function (type) {
            return typeof type === "string" ? type : (type.name || ("" + type));
        };

        if ("name" in _properties._this) {
            Object.defineProperties(this, {
                name: { value: _properties._this.name },
                displayName: { value: _properties._this.name }
            });
        }

        // Copy over default property configurations to each property definition
        for (var prop in _properties) {
            if (prop !== "_this") {
                for (var conf in _properties._this.defaults) {
                    if (!(conf in _properties[prop])) _properties[prop][conf] = _properties._this.defaults[conf];
                }
            }
        }

        if (_valid) {
            // Validating the passed object
            for (var prop in _properties) {
                // Skip the special _this property
                if (prop === "_this") continue;

                // Is the property present?
                if (prop in obj) {
                    // Does the type match?
                    if (isType(obj[prop], _properties[prop].type)) continue;
                // Is the property required?
                } else if (!_properties[prop].required) continue;

                _valid = false;
                _invalidAt = prop;
                break;
            }
        }

        if (!_valid) {
            var expected = {
                str: typeName(_properties._this.type) + " {",
                idx: {}  // Can be used later to give a little arrow pointing to it instead of the >
            };
            for (var prop in _properties) {
                if (prop !== "_this") {
                    if (!_properties[prop].required) expected.str += "[";
                    if (_invalidAt === prop) expected.str += ">";
                    expected.idx[prop] = expected.str.length - 1;
                    expected.str += prop + ":" + typeName(_properties[prop].type);
                    if (!_properties[prop].required) expected.str += "]";
                    expected.str += ", ";
                }
            }
            expected.str = expected.str.substring(0, expected.str.length - 2) + "}";

            throw new TypeError("Invalid argument passed, expecting: " + expected.str);
        }

        for (var prop in _properties) {
            if (prop !== "_this") {
                // The camel-cased property name is ok to be saved in the static _properties object since it's imperatively dependend on the property's name anyway
                _properties[prop].camelized =  prop.replace(/[\s_-]{2,}/g, function ($0) { return $0[0]; }).replace(/(?:^\s*|\s+|[_-])(.)/g, function ($0, $1) { return $1.toUpperCase(); });

                // This is mainly done for making extending this later on easier.
                // If this may ever be extended to have, for example, protected properties as well,
                // or more functionality that accesses the value storages is added, then the _values object
                // will be much nicer to work with then having to add if/else cases everywhere.
                if (_properties[prop].static === true) {
                    _staticStorage[prop] = obj[prop] || undefined;
                    Object.defineProperty(_values, prop, {
                        get: (function (prop) { return _staticStorage[prop]; }).bind(this, prop),
                        set: (function (prop, value) { return _staticStorage[prop] = value; }).bind(this, prop)
                    });
                } else {
                    _privateStorage[prop] = obj[prop] || undefined;
                    Object.defineProperty(_values, prop, {
                        get: (function (prop) { return _privateStorage[prop]; }).bind(this, prop),
                        set: (function (prop, value) { return _privateStorage[prop] = value; }).bind(this, prop)
                    });
                }

                var getter = (function (prop) {
                    return _values[prop];
                }).bind(this, prop);

                var setter = (function (prop, val) {
                    if (_properties[prop].strictSetter && !isType(val, _properties[prop].type)) {
                        throw new TypeError(prop + " must be of type " + typeName(_properties[prop].type));
                    }

                    _values[prop] = val;

                    // This totally works and it's awesomely convenient
                    // (returns the assigned value with the native setters but the object with the setter methods)
                    return self;
                }).bind(this, prop);

                if (_properties[prop].public) {
                    Object.defineProperty(this, prop, {
                        get: getter,
                        set: setter,
                        configurable: false,
                        enumerable: true
                    });
                }

                if (_properties._this.getters) {
                    Object.defineProperty(this, "get" + _properties[prop].camelized, {
                        value: getter,
                        writable: false,
                        configurable: false,
                        enumerable: false
                    });
                }

                if (_properties._this.setters) {
                    Object.defineProperty(this, "set" + _properties[prop].camelized, {
                        value: setter,
                        writable: false,
                        configurable: false,
                        enumerable: false
                    });
                }
            }
        }

        Object.defineProperty(this, "isValid", {
            value: function () { return _valid; },
            writable: false,
            configurable: false,
            enumerable: false
        });
    };

    return {
        objectify: objectify,
        GenericObject: GenericObject
    };
})();

objectify_examples.js

/**
 * These are some simple usage examples of objectify.js.
 * Just copy-paste objectify.js and these examples into the JS console of your choice and see for yourself!
 */

var dummyConfig = {
    _this: {
        name: "DummyObject",
        type: "object",
        getters: true,
        setters: true,
        defaults: {
            strictSetter: true,
            public: false
        }
    },
    data: {
        required: true,
        type: "string",
    },
    staticData: {
        required: false,
        type: "string",
        strictSetter: false,
        static: true
    },
    publicData: {
        required: false,
        type: "string",
        public: true
    },
    time: {
        required: false,
        type: Date
    }
};

var DummyObject = Objectify.objectify(dummyConfig);


// Catch any thrown error and output it to console.error
function test(fun) {
    try {
        console.log("> " + fun.toString().replace(/^\s*(?:function\s*\(\s*\)|\(\s*\)\s*=\s*>)\s*\{\s*(?:return)?/, '').replace(/}$/, '').replace(/^\s*|\s*$/g, ''));
        let ret = fun.call();
        console.log(ret instanceof Object ? ret : JSON.stringify(ret));
    } catch (e) {
        console.error("ERROR:", e);
    }
}


test(()=>{  new DummyObject();                                     });
test(()=>{  DummyObject({data: "test data", time: new Date()});    });
test(()=>{  new DummyObject({ faultyData: "uh-oh" });              });

console.log("");
console.log("");

var d1 = new DummyObject({
    data: "Hello World!",
    time: new Date()
});
var d2 = new DummyObject({
    data: "This object has no time"
});

test(()=>{ return  d1.data;                 /* => undefined */ });
test(()=>{ return  d1.getData();            /* => "Hello World!" */ });
test(()=>{ return  d2.getData();            /* => "This object has no time" */ });

console.log("");

test(()=>{ return  d2.getTime();            /* => undefined */ });
test(()=>{ return  d2.setTime(1337);        /* => ERROR: TypeError: time must be of type Date */ });
test(()=>{ return  d2.setTime(new Date());  /* => DummyObject { ... */ });
test(()=>{ return  d2.getTime();            /* => Wed Jan 31 2018 ... */ });

console.log("");

test(()=>{ return  d1.getStaticData();      /* => undefined */ });
test(()=>{ return  d2.setStaticData(3.14);  /* => DummyObject { ... */ });
test(()=>{ return  d1.getStaticData();      /* => 3.14 */ });

console.log("");

test(()=>{ return  d1.publicData = "this is an enumerable property";   /* => "this is an enumerable property" */ });
test(()=>{         for (var p in d1) { console.log(p, ":", d1[p]); };  /* => publicData : this is ... */ });
test(()=>{ return  JSON.stringify(d1);                                 /* => "{\"publicData\":\"this is an enumerable property\"}" */ });

TODOs:

• add "strict" and "non-strict" type checking, autoconvert values on non-strict => maybe just use setters/getters...?
• custom getter/setter per property
• custom validator per property
• nicer error message, maybe allow for descriptions of properties
• documentation?!?!?!??!?!?!?!??!?!?!?!??!
  • surely examples are documentation enough

ETA: whenever I feel like it. Probably never.

shit's tite yo