OOP support.

doc/src/language/oop.md

@@ -0,0 +1,44 @@
+Object-Oriented Programming (OOP)
+================================
+
+{{#include ../links.md}}
+
+Rhai does not have _objects_ per se, but it is possible to _simulate_ object-oriented programming.
+
+
+Use [Object Maps] to Simulate OOP
+--------------------------------
+
+Rhai's [object maps] has [special support for OOP]({{rootUrl}}/language/object-maps-oop.md).
+
+| Rhai concept                                          | Maps to OOP |
+| ----------------------------------------------------- | :---------: |
+| [Object maps]                                         |   objects   |
+| [Object map] properties holding values                | properties  |
+| [Object map] properties that hold [function pointers] |   methods   |
+
+
+Examples
+--------
+
+```rust
+// Define the object
+let obj = #{
+                data: 0,
+                increment: Fn("add"),       // when called, 'this' binds to 'obj'
+                update: Fn("update"),       // when called, 'this' binds to 'obj'
+                action: Fn("action")        // when called, 'this' binds to 'obj'
+           };
+
+// Define functions
+fn add(x)       { this.data += x; }         // update using 'this'
+fn update(x)    { this.data = x; }          // update using 'this'
+fn action()     { print(this.data); }       // access properties of 'this'
+
+// Use the object
+obj.increment(1);
+obj.action();                               // prints 1
+
+obj.update(42);
+obj.action();                               // prints 42
+```