Changes between Version 11 and Version 12 of Classes

Timestamp:

05/16/10 12:58:30 (15 years ago)

Author:

hopscc

Comment:

expand Properties, cleanup

Classes

@@ -109 +109 @@
 
 == Properties ==
-Define a property for the class
-
-''To be expanded''
-
-=== Properties Grammar ===
-
-{{{
-get <propName> [ as {<Type>, var}] [is <accessModifier>]
-set <propName> [ as {<Type>, var}   [is <accessModifier>]
-
-pro <propName> [ as {<Type>, var}] [is <accessModifier>]
-
-pro <propName> [is <accessModifier>]
-
+''This discussion is somewhat simplified for clarity.[[BR]]
+Please see
+[wiki:Property Properties]''
+
+Properties are members that provide a flexible mechanism to read, write, or compute the values of private fields. [[BR]]
+They  are used as if they are public data members, but are actually implemented via special methods called accessors.
+
+There are 3 keywords for defining a property:[[BR]]
+'''get''' defines a readOnly property ( Can access the properties value but cant change it). [[BR]]
+'''set''' defines a writeOnly property (Can write to the property but cant read it)[[BR]]
+'''pro''' defines a readable and writable property.
+
+If a property accessor merely reflects a protected or private backing variable (field) you can[[BR]]
+use a clause beginning with keyword '''from'''.
+  *  '''from var''' [[BR]]
+    {{{ pro <name> from var }}} or {{{get <name> from var}}} or {{{ set <name> from var}}}[[BR]]
+    The property will get or set its value unchanged from a backing variable named 
+    to the property name with a single underscore prepended to it. 
+      * If there is no backing variable but there is an assignment to the property or a type declaration on the property
+        the backing variable will be implicitly created for you.
+  * ''' from <backingVarName>'''[[BR]]
+    Otherwise the word following the '''from''' must be the name of an existing backing store variable.
+
+Finally if an accessor needs to translate, filter or modifies in some way a backing variable or computes a value[[BR]]
+there is a longer syntax variant where either of both the get and set accessors can be specified and a block of code[[BR]] 
+provided to store (setter) or generate (getter) the property value. 
+
+=== (Simplified) Properties Grammar ===
+
+{{{
+get <propName> [ as <Type>] [from {var, <backingVariableName>} [= <initValue>] ]
+    [<DocString>]
+
+set <propName> [ as <Type>] [from {var, <backingVariableName>} [= <initValue>] ] 
+    [<DocString>]
+
+pro <propName> [ as <Type>] [from {var, <backingVariableName>} [= <initValue>] ] 
+    [<DocString>]
+
+# full accessor variant, one or both of 'get' and 'set blocks must be present.
+pro <propName> 
     get 
         [...]
         return <value>
     set
-        [...] # assign or otherwise do something with implicit arg "value" (passed in) to something 
-
-}}}
+        [...] # assign or otherwise do something with implicit arg "value" (passed in) 
+
+}}}
+
+=== Property Example ===
+{{{
+var _x  = 47
+pro x from var     # property x uses backing var _x
+# above same as 
+#pro x from _x
+}}}
+
+Can do all of the above in one line like
+{{{
+pro x = 47
+# or
+pro x as int = 47
+}}}
+
+Above is equivalent to fully specified accessor form
+{{{
+var _x = 47
+pro
+    get
+        return _x
+    set
+        _x = value
+
+}}}
+
+
 
 == Methods ==
@@ -203 +258 @@
 sum takes a variable number of integer args.
 
-
-== Generics ==
-+++TBD+++ Generics
-
-
-++accessing baseclass methods
+== TBD ==
+
+''Generics''
+
+''accessing baseclass methods''