Difference between revisions of "Inherited"
From Lazarus wiki
Jump to navigationJump to search (virtual method override example) |
|||
Line 51: | Line 51: | ||
end; | end; | ||
... | ... | ||
+ | </syntaxhighlight> | ||
+ | |||
+ | == virtual methods override == | ||
+ | |||
+ | <syntaxhighlight lang="pascal"> | ||
+ | type | ||
+ | TMyClass = class(TStrings) | ||
+ | function GetObject(Index: Integer): TObject; override; | ||
+ | end; | ||
+ | |||
+ | function TMyClass.GetObject(Index: Integer): TObject; | ||
+ | begin | ||
+ | // Get result from parent class method | ||
+ | Result := inherited GetObject(Index); | ||
+ | // Do something | ||
+ | end; | ||
</syntaxhighlight> | </syntaxhighlight> |
Revision as of 09:16, 10 February 2020
│
Deutsch (de) │
English (en) │
suomi (fi) │
français (fr) │
русский (ru) │
In an overridden virtual method, it is often necessary to call the parent class
’ implementation of the virtual method.
This can be done with the inherited
reserved word. Likewise, the inherited
keyword can be used to call any method of the parent class
.
This case is the simplest:
Type
TMyClass = Class(TComponent)
Constructor Create(AOwner : TComponent); override;
end;
Constructor TMyClass.Create(AOwner : TComponent);
begin
Inherited;
// Do more things
end;
constructors and destructors case
Constructor
, example 1 :
...
TTest.Create;
begin
Inherited; // Always at the beginning of the constructors and start the constructor (code only) of the parent class
...
end;
Constructor
, example 2 :
...
TTest.Create(...);
begin
Inherited Create(...); // Always at the beginning of the constructors and start the constructor (code only) of the parent class
...
end;
...
Destructor
, example 3 :
TTest.Destroy;
begin
...
Inherited; // Always at the end of the destructors and start the destructor (code only) of the parent class
end;
...
virtual methods override
type
TMyClass = class(TStrings)
function GetObject(Index: Integer): TObject; override;
end;
function TMyClass.GetObject(Index: Integer): TObject;
begin
// Get result from parent class method
Result := inherited GetObject(Index);
// Do something
end;