API: Script Keys and Objects
#ScriptObjectKeys ScriptObjectKeys and ScriptObjectKey are the underpinnings of the type system used by all scriptable objects in libscriptobject.
A key is made up from a field name and type (string, int, null, etc.), objects have one or more keys which ultimately describe the type of the object. Consider:
var x = { pi: 3.14159, theAnswer: 42 };
var y = { theAnswer: -42, pi: -3.14159 };These two objects, x and y, have fields pi and theAnswer which have the same type in both objects. Inside libscriptobject the object instances x and y have keys which are used to describe the object, if we were to compare the keys (name and field type) then we could say the objects are the same 'type' since they are equivalent at the key level:
var x = { pi: double, theAnswer: integer };
var y = { pi: double, theAnswer: integer }; // note the field order has changedObjects with identical keys can share those keys, resulting in only one instance of an object 'type'. Changing a field name, type, or number of fields either results in a new 'type' or the object sharing a common key object matching that new type.
Being able to track type equivalence for scriptable objects is a useful optimization; we can store a single instance of the keys describing the type and refer to that instance from all type-equivalent objects.
This technique saves both memory and CPU time but has a number of limitations:
- What happens when fields change type or when fields are removed or added?
- What happens if objects contain fields with random-like names (timestamps, GUIDs, etc.)?
Both of these issues defeat the type system but can be mitigated by libscriptobject:
- Fields can be removed from objects, this results in the creation of a new object with new keys
- Fields can be added to an object, this is done by merging objects together - much like JavaScript's
Object.assign()function. - When objects are declared that are known to have random-like field names the caller can elect out of sharing the object's keys.
