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2000-06-25 10:24 UTC+0800 Brian Hays <bhays@abacuslaw.com>

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Brian Hays
2000-06-26 05:30:44 +00:00
parent 4f5dd5cb17
commit 1ebd0b679b
1 changed files with 117 additions and 90 deletions
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207
harbour/doc/en/command.txt
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@@ -15,34 +15,51 @@
/* $DOC$
* $COMMANDNAME$
* CLASS
* [CREATE] CLASS
* $CATEGORY$
* Oop Command
* OOP Command
* $ONELINER$
* Define a Class for Object Oriented Programming
* $SYNTAX$
* CLASS <ClassName> [ <FROM, INHERIT> <SuperClass> ]
* [CREATE] CLASS <ClassName> [ <FROM, INHERIT> <SuperClass1> [,<SuperClassN>] ] [STATIC]
* $ARGUMENTS$
* <ClassName> Name of the class to define. By tradition, Harbour
* classes start with "T" to avoid collisions with user-
* created classes.
* created classes.
*
* <SuperClass1...n> The Parent class(es) to use for inheritance.
* Harbour supports Multiple Inheritance.
*
* STATIC This clause causes the class function to be declared
* as a static function. It will therefore not be available outside the current module.
*
* <SuperClass> The Parent class to use for inheritance
* $DESCRIPTION$
* CLASS creates a class from which you can create objects.
* Each Class is defined in a separate .PRG file dedicated to that
* purpose. You cannot create more than one class in a .PRG.
* After the CLASS command begins the definition, the DATA
* The CLASS command begins the class specification, in which the DATA
* elements (also known as instance variables) and METHODS of the
* class are named.
* class are named. The following scoping commands may also appear.
* They control the default scope of DATA and METHOD commands that follow them.
<fixed>
EXPORTED:
VISIBLE:
HIDDEN:
PROTECTED:
</fixed>
*
* Classes can inherit from a single <SuperClass>, but the chain of
* inheritance can extend to many levels.
* The class specification ends with the END CLASS command.
*
* A program uses a Class by calling the Class Constructor, the
* Classes can inherit from multiple <SuperClasses>, and the chain of
* inheritance can extend to many levels.
*
* A program uses a Class by calling the Class Constructor, usually the
* New() method, to create an object. That object is usually assigned
* to a variable, which is used to access the DATA elements and
* methods.
* methods.
*
* Harbour's OOP syntax and implementation supports Scoping (Protect, Hidden and Readonly)
* and Delegating, and is largely compatible with Class(y)(tm), TopClass(tm)
* and Visual Objects(tm).
*
* $EXAMPLES$
<fixed>
* CLASS TBColumn
@@ -66,9 +83,9 @@
* $STATUS$
* R
* $COMPLIANCE$
* CLASS is a Harbour extension.
* CLASS is a Harbour extension.
* $PLATFORMS$
* All
* All
* $SEEALSO$
* TClass(),Object Oriented Programming,DATA,METHOD
* $END$
@@ -78,42 +95,52 @@
* $COMMANDNAME$
* DATA
* $CATEGORY$
* Oop Command
* OOP Command
* $ONELINER$
* Define a DATA instance variable for the objects of a class
* Alternate syntax for VAR: instance variable for the objects.
* $SYNTAX$
* DATA <DataName1> [,<DataNameN>] [ AS <type> ] [ INIT <uValue> ]
* [ EXPORTED] [PROTECTED] [HIDDEN] [ READONLY]
* [[EXPORTED | VISIBLE] | [PROTECTED] | [HIDDEN]] [READONLY | RO]
* $ARGUMENTS$
* <DataName1> Name of the DATA
* <DataName1> Name of the DATA
* <type> Optional data type specification from the following:
* Character, Numeric, Date, Logical, Codeblock, Nil
* Character, Numeric, Date, Logical, Codeblock, Nil.
* <uValue> Optional initial value when creating a new object
* <uValue> Optional initial value when creating a new object.
*
* EXPORTED This clause tell that this data is visible in where
* was defined and all subclasses.
* EXPORTED Specifies that this DATA is accessible to functions and
* methods outside of the class. VISIBLE is a synonym for EXPORTED.
*
* PROTECTED This clause tell that the data is visible only where is
* defined
* PROTECTED Specifies that this DATA is only accessible to functions and methods within this class and its subclasses.
*
* HIDDEN This clause say that the data is only visible on the
* class that was defined,and is not inherit by the
* HIDDEN Specifies that this DATA is only accessible to the
* class where it was defined, and is not inherited by the
* subclasses.
* READONLY Restricts assignment to the variable. If specified with
* the EXPORTED clause, assignment is only permitted from the current
* class and its subclasses. If specified with the PROTECTED clause,
* assignment is only permitted from the current class.
* RO is a synonym for READONLY.
* $DESCRIPTION$
* DATA elements can also be thought of as the "properties" of an
* object. They can be of any data type, including codeblock.
* Once an object has been created, the DATA elements are referenced
* with the colon (:) as in MyObject:Heading := "Last name".
* Usually a class also defines methods to manipulate the DATA.
* Usually a class also defines methods to manipulate the DATA.
*
* You can use the "AS <type>" clause to enforce that the DATA is
* maintained as a certain type. Otherwise it will take on the type of
* whatever value is first assigned to it.
* whatever value is first assigned to it.
*
* Use the "INIT <uValue>" clause to initialize that DATA to <uValue>
* whenever a new object is created.
* whenever a new object is created.
*
* VAR can be a synonym for DATA, or it can use a slightly different
* syntax for compatibility with other dialects.
* $EXAMPLES$
<fixed>
* CLASS TBColumn
@@ -136,11 +163,11 @@
* $STATUS$
* R
* $COMPLIANCE$
* DATA is a Harbour extension.
* DATA is a Harbour extension.
* $PLATFORMS$
* All
* All
* $SEEALSO$
* Object Oriented Programming,CLASS,METHOD,CLASSDATA
* Object Oriented Programming,CLASS,METHOD,CLASSDATA,VAR
* $END$
*/
@@ -148,18 +175,18 @@
* $COMMANDNAME$
* CLASSDATA
* $CATEGORY$
* Oop Command
* OOP Command
* $ONELINER$
* Define a CLASSDATA variable for a class (NOT for an Object!)
* $SYNTAX$
* CLASSDATA <DataName1> [,<DataNameN>] [ AS <type> ] [ INIT <uValue> ]
* CLASSDATA <DataName1> [,<DataNameN>] [ AS <type> ] [ INIT <uValue> ]
* $ARGUMENTS$
* <DataName1> Name of the DATA
* <DataName1> Name of the DATA
* <type> Optional data type specification from the following:
* Character, Numeric, Date, Logical, Codeblock, Nil
* Character, Numeric, Date, Logical, Codeblock, Nil
* <uValue> Optional initial value at program startup
* <uValue> Optional initial value at program startup
* $DESCRIPTION$
* CLASSDATA variables can also be thought of as the "properties" of an
* entire class. Each CLASSDATA exists only once, no matter how many
@@ -170,9 +197,9 @@
*
* You can use the "AS <type>" clause to enforce that the CLASSDATA is
* maintained as a certain type. Otherwise it will take on the type of
* whatever value is first assigned to it.
* whatever value is first assigned to it.
* Use the "INIT <uValue>" clause to initialize that DATA to <uValue>
* whenever the class is first used.
* whenever the class is first used.
* $EXAMPLES$
<fixed>
* CLASS TWindow
@@ -183,9 +210,9 @@
* $STATUS$
* R
* $COMPLIANCE$
* CLASSDATA is a Harbour extension.
* CLASSDATA is a Harbour extension.
* $PLATFORMS$
* All
* All
* $SEEALSO$
* Object Oriented Programming,CLASS,METHOD,DATA
* $END$
@@ -195,7 +222,7 @@
* $COMMANDNAME$
* METHOD
* $CATEGORY$
* Oop Command
* OOP Command
* $ONELINER$
* Declare a METHOD for a class in the class header
* $SYNTAX$
@@ -208,27 +235,27 @@
* METHOD <MethodName>( [<param>] ) OPERATOR <op>
* METHOD <MethodName>( [<params,...>] ) CLASS <ClassName>
* $ARGUMENTS$
* <MethodName> Name of the method to define
* <MethodName> Name of the method to define
* <params,...> Optional parameter list
* <params,...> Optional parameter list
* $DESCRIPTION$
* Methods are "class functions" which do the work of the class.
* All methods must be defined in the class header between the
* CLASS and ENDCLASS commands. If the body of a method is not fully
* defined here, the full body is written below the ENDCLASS command
* using this syntax:
* using this syntax:
*
* METHOD <MethodName>( [<params,...>] ) CLASS <ClassName>
* METHOD <MethodName>( [<params,...>] ) CLASS <ClassName>
*
* Methods can reference the current object with the keyword "Self:" or
* its shorthand version "::".
*
* CLAUSES:
* its shorthand version "::".
*
* CLAUSES:
*
* CONSTRUCTOR Defines a special method Class Constructor method,
* used to create objects. This is usually the
* New() method. Constructors always return the new
* object.
* object.
*
* INLINE Fast and easy to code, INLINE lets you define the
* code for the method immediately within the definition
@@ -236,31 +263,31 @@
* must be fully defined after the ENDCLASS command.
* The <Code,...> following INLINE receives a parameter
* of Self. If you need to receive more parameters, use
* the BLOCK clause instead.
* the BLOCK clause instead.
*
* BLOCK Use this clause when you want to declare fast 'inline'
* methods that need parameters. The first parameter to
* <CodeBlock> must be Self, as in:
* <CodeBlock> must be Self, as in:
*
* METHOD <MethodName> BLOCK {|Self,<arg1>,<arg2>, ...,<argN>|...}
* METHOD <MethodName> BLOCK {|Self,<arg1>,<arg2>, ...,<argN>|...}
*
* EXTERN If an external function does what the method needs,
* use this clause to make an optimized call to that
* function directly.
*
* function directly.
*
* SETGET For calculated Data. The name of the method can be
* manipulated like a Data element to Set or Get a value.
* manipulated like a Data element to Set or Get a value.
*
* VIRTUAL Methods that do nothing. Useful for Base classes where
* the child class will define the method's behavior, or
* when you are first creating and testing a Class.
* when you are first creating and testing a Class.
*
* OPERATOR Operator Overloading for classes.
* See example Tests/TestOp.prg for details.
* See example Tests/TestOp.prg for details.
*
* CLASS <ClassName>
* CLASS <ClassName>
* Use this syntax only for defining a full method after
* the ENDCLASS command.
* the ENDCLASS command.
* $EXAMPLES$
<fixed>
* CLASS TWindow
@@ -287,9 +314,9 @@
* $STATUS$
* R
* $COMPLIANCE$
* METHOD is a Harbour extension.
* METHOD is a Harbour extension.
* $PLATFORMS$
* All
* All
* $SEEALSO$
* TClass(),Object Oriented Programming,DATA,CLASS
* $END$
@@ -299,36 +326,36 @@
* $COMMANDNAME$
* MESSAGE
* $CATEGORY$
* Oop Command
* OOP Command
* $ONELINER$
* Route a method call to another Method
* $SYNTAX$
* MESSAGE <MessageName> METHOD <MethodName>( [<params,...>] )
* MESSAGE <MessageName>() METHOD <MethodName>( [<params,...>] )
* $ARGUMENTS$
* <MessageName> The pseudo-method name to define
* <MessageName> The pseudo-method name to define
* <MethodName> The method to create and call when <MessageName>
* is invoked.
* is invoked.
* <params,...> Optional parameter list for the method
* <params,...> Optional parameter list for the method
* $DESCRIPTION$
* The MESSAGE command is a seldom-used feature that lets you re-route
* a call to a method with a different name. This can be necessary if
* a method name conflicts with a public function that needs to be
* called from within the class methods.
* called from within the class methods.
*
* For example, your app may have a public function called BeginPaint()
* that is used in painting windows. It would also be natural to have a
* Window class method called :BeginPaint() that the application can
* call. But within the class method you would not be able to call the
* public function because internally methods are based on static
* functions (which hide public functions of the same name).
* functions (which hide public functions of the same name).
*
* The MESSAGE command lets you create the true method with a different
* name (::xBeginPaint()), yet still allow the ::BeginPaint() syntax
* to call ::xBeginPaint(). This is then free to call the public
* function BeginPaint().
* function BeginPaint().
* $EXAMPLES$
<fixed>
* CLASS TWindow
@@ -340,9 +367,9 @@
* $STATUS$
* R
* $COMPLIANCE$
* MESSAGE is a Harbour extension.
* MESSAGE is a Harbour extension.
* $PLATFORMS$
* All
* All
* $SEEALSO$
* METHOD,DATA,CLASS,Object Oriented Programming
* $END$
@@ -352,18 +379,18 @@
* $COMMANDNAME$
* ERROR HANDLER
* $CATEGORY$
* Oop Command
* OOP Command
* $ONELINER$
* Designate a method as an error handler for the class
* $SYNTAX$
* ERROR HANDLER <MethodName>( [<params,...>] )
* $ARGUMENTS$
* <MethodName> Name of the method to define
* <MethodName> Name of the method to define
* <params,...> Optional parameter list
* <params,...> Optional parameter list
* $DESCRIPTION$
* ERROR HANDLER names the method that should handle errors for the
* class being defined.
* class being defined.
* $EXAMPLES$
<fixed>
* CLASS TWindow
@@ -373,9 +400,9 @@
* $STATUS$
* R
* $COMPLIANCE$
* ERROR HANDLER is a Harbour extension.
* ERROR HANDLER is a Harbour extension.
* $PLATFORMS$
* All
* All
* $SEEALSO$
* Object Oriented Programming,ON ERROR,CLASS,METHOD,DATA
* $END$
@@ -385,19 +412,19 @@
* $COMMANDNAME$
* ON ERROR
* $CATEGORY$
* Oop Command
* OOP Command
* $ONELINER$
* Designate a method as an error handler for the class
* $SYNTAX$
* ON ERROR <MethodName>( [<params,...>] )
* $ARGUMENTS$
* <MethodName> Name of the method to define
* <MethodName> Name of the method to define
* <params,...> Optional parameter list
* <params,...> Optional parameter list
* $DESCRIPTION$
* ON ERROR is a synonym for ERROR HANDLER.
* It names the method that should handle errors for the
* class being defined.
* class being defined.
* $EXAMPLES$
<fixed>
* CLASS TWindow
@@ -407,9 +434,9 @@
* $STATUS$
* R
* $COMPLIANCE$
* ON ERROR is a Harbour extension.
* ON ERROR is a Harbour extension.
* $PLATFORMS$
* All
* All
* $SEEALSO$
* Object Oriented Programming,ERROR HANDLER,CLASS,METHOD,DATA
* $END$
@@ -419,14 +446,14 @@
* $COMMANDNAME$
* ENDCLASS
* $CATEGORY$
* Oop Command
* OOP Command
* $ONELINER$
* End the declaration of a class.
* $SYNTAX$
* ENDCLASS
* ENDCLASS
* $DESCRIPTION$
* ENDCLASS marks the end of a class declaration.
* It is usually followed by the class methods that are not INLINE.
* ENDCLASS marks the end of a class declaration.
* It is usually followed by the class methods that are not INLINE.
* $EXAMPLES$
<fixed>
* CLASS TWindow
@@ -436,9 +463,9 @@
* $STATUS$
* R
* $COMPLIANCE$
* ON ERROR is a Harbour extension.
* ON ERROR is a Harbour extension.
* $PLATFORMS$
* All
* All
* $SEEALSO$
* Object Oriented Programming,CLASS,METHOD,DATA
* $END$