Jsctypes/api: Difference between revisions

Jsctypes/api (view source)

187 bytes added , 29 September 2009

→‎CData objects: try to clarify aliasing example

638

edits

@@ Line 302: / Line 302: @@
 ''(TODO: Pointer types might need some properties of their own.)''
-It is possible for multiple <code>CData</code> objects to refer to the same memory. (In this way they are sort of like C++ references.) For example:
+Note that it is possible for several <code>CData</code> objects to refer to the same or overlapping memory. (In this way <code>CData</code> objects are like C++ references.) For example:
   const Point = new ctypes.StructType(
@@ Line 310: / Line 310: @@
   var r = Rect();     // a new CData object of type Rect
-  r.topLeft.x = 100;  // This works because r.topLeft is a CData object
+ var p = r.topLeft;  // refers to the topLeft member of r, not a copy
-                     // that refers to the topLeft member of r, not a copy.
+  r.topLeft.x = 100;  // This would not work if `r.topLeft` was a copy!
+ r.topLeft.x
+   ===> 100          // It works...
+ p.x                 // and p refers to the same C/C++ object...
+   ===> 100          // so it sees the change as well.
   r.toSource()
-  ===> "Rect({topLeft: Point({x: 100, y: 0}), bottomRight: Point({x: 0, y: 0})})"
+  ===> "Rect({topLeft: {x: 100, y: 0}, bottomRight: {x: 0, y: 0}})"
 Minutiae: