Changes between Version 12 and Version 13 of MixIn

Timestamp:

07/29/13 11:50:07 (11 years ago)

Author:

hopscc

Comment:

--

MixIn

@@ -3 +3 @@
 == Introduction ==
 
-To be done. In the mean time, see the [http://cobra-language.com/forums/viewtopic.php?f=4&t=306 discussion thread].
+Provide a non inheritance based capability for shared/common behaviour.
+
+Basically, selected traits or behaviours are described in a special Type called a 'mixin' (analogous to an interface),[[BR]]
+these can then be specified on a class and are injected into that class to provide those behaviours on that class.  
+
+
+Mixin behaviours can be specified using object:
+  * vars
+  * properties
+  * methods
+They do not support constructors
+
+(For more see the [http://cobra-language.com/forums/viewtopic.php?f=4&t=306 Forum discussion thread]).
 
 == Compared to Extensions ==
@@ -14 +26 @@
  * Mixins cannot be used from a [wiki:BinaryLibrary binary library]. The source must be included for the compiler.
 
-In summary, mixins are more about multiple inheritance among the types you are declaring. Extensions are about adding convenience methods to existing types (regardless of who declared them).
+In summary, mixins are more about implementing shared capabilities among the types you are declaring. [[BR]]
+Extensions are about adding convenience methods to existing types (regardless of who declared them).
 
 == Restrictions ==
@@ -28 +41 @@
  * Two or more mixins added to a single type cannot have collision in their member names.
 
+== Example ==
+{{{
+#!cobra
+
+# The behaviour desired - a name property
+mixin Named
+    var _name as String?
+    pro name as String
+        get
+            return _name ? ''
+        set
+            _name = value
+
+   get capName
+        return _name[:1].toUpper + _name[1:]
+        
+        
+# the (otherwise empty) class with mixin added
+class A adds Named      
+    pass
+
+def main is shared
+    a = A()
+    assert a inherits Named
+    assert a.name == ''
+    a.name = 'arosebyanyothername'
+    assert a.name == 'arosebyanyothername'
+    assert a.capName == 'Arosebyanyothername'
+}}}
+
 == See also ==