Changes between Initial Version and Version 1 of Struct

Timestamp:

05/14/10 13:22:52 (15 years ago)

Author:

hopscc

Comment:

--

Struct

@@ +1 @@
+= Struct Definition = 
+
+Structs are similar to classes but more limited in ways that make them suitable [[BR]]
+for representing lightweight value-container-only objects ( like a Point or Rectangle).
+
+Unlike classes (reference type) they are a value type and they cannot be inherited or inherit[[BR]]
+from another class or struct. 
+
+Other differences from classes:[[BR]]
+    * Within a struct declaration, fields cannot be initialized unless they are declared as const or static.
+    * A struct may not declare a default constructor (a constructor without parameters) or a destructor.
+    * Structs can only declare constructors that have parameters.
+    * Structs are copied on assignment and when passed into methods. [[BR]]
+      When a struct is assigned to a new variable or passed to a method, all the data is copied, and any modification to the [[BR]]
+      new copy does not change the data for the original copy. 
+
+However
+    * A struct can implement interfaces.
+    * A struct can be used as a nullable type and can be assigned a null value.
+
+Structures and their contained instance members are public by default though this may be[[BR]]
+overridden using the normal [wiki:AccessModifiers access modifiers] syntax.
+
+Idomatic usage suggests structs should not modify their accessmodifiers for visibility and[[BR]]
+should not declare any methods (If this is deemed necessary you should use a class instead).[[BR]]
+They should only be used as publicly accessible value containers. 
+
+The syntax/grammar for declaring structures is similar to that of classes [[BR]]
+(barring the '''struct''' keyword and lack of the '''inherits''' clause)
+
+== Grammar ==
+{{{
+struct <StructureName>  
+    [is <AccessModifiers>]
+    [has <Attributes>]
+    [where <GenericParam> must be <GenericConstraints>]
+    [implements <InterfaceName> [, <InterfaceName>]...]
+    [<DocString>]
+    [
+        [<Variables>]
+        [<Constants>]
+        [<Properties>]
+        [<Methods>
+        [<Enums>]
+        [<Sigs>]
+        [<Invariants>]
+        [<Tests>]
+        [<SharedClause>]
+    ]...
+
+# empty (placeholder) structure
+struct <StructureName>  
+    [is <AccessModifiers>]
+    [has <Attributes>]
+    [where <GenericParam> must be <GenericConstraints>]
+    [implements <InterfaceName> [, <InterfaceName>]...]
+    [<DocString>]
+        pass
+}}}
+
+== Platform ==
+
+in .Net,  all structs inherit directly from System.!ValueType, which inherits from System.Object.
+
+== Examples ==
+{{{
+# a simple Point-like struct
+struct CoOrds
+    var x as int
+    var y as int
+
+    cue init(p1 as int, p2 as int)
+        .x = p1
+        .y = p2
+
+
+#// Declare and initialize struct objects.
+class TestCoOrds
+    def main is shared
+        # Initialize:   
+        coords1 = CoOrds()
+        coords2 = CoOrds(10, 10)
+
+        # Display results:
+        print 'CoOrds 1: ' stop
+        print 'x = [coords1.x], y = [coords1.y]'
+
+        print 'CoOrds 2: ' stop
+        print 'x = [coords2.x], y = [coords2.y]'
+        
+        assert coords1.x == 0 and coords1.y == 0
+        assert coords2.x == 10 and coords2.y == 10
+
+/# Output:
+    CoOrds 1: x = 0, y = 0
+    CoOrds 2: x = 10, y = 10
+#/
+
+
+}}}
+
+== Notes ==
+
+== See Also ==
+[http://msdn.microsoft.com/en-us/library/ah19swz4.aspx struct(C# Reference)]
+
+[http://msdn.microsoft.com/en-us/library/saxz13w4.aspx Structs(C# Programming Guide)]
+
+[http://msdn.microsoft.com/en-us/library/0taef578.aspx Using Structs( C# Programming Guide)]
+
+
+[wiki:LanguageTopics Back to LanguageTopics]