Difference between revisions of "Inherited"
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| − | {{ | + | {{Inherited}} |
| − | + | ||
| − | In an overridden virtual method, it is often necessary to call the parent | + | |
| + | In an overridden virtual [[Method|method]], it is often necessary to call the parent [[Class|<syntaxhighlight lang="pascal" enclose="none">class</syntaxhighlight>]]’ implementation of the virtual method. | ||
| + | This can be done with the <syntaxhighlight lang="pascal" enclose="none">inherited</syntaxhighlight> [[Reserved word|reserved word]]. Likewise, the <syntaxhighlight lang="pascal" enclose="none">inherited</syntaxhighlight> [[Keyword|keyword]] can be used to call any method of the parent <syntaxhighlight lang="pascal" enclose="none">class</syntaxhighlight>. | ||
This case is the simplest: | This case is the simplest: | ||
| Line 16: | Line 18: | ||
// Do more things | // Do more things | ||
end; | end; | ||
| + | </syntaxhighlight> | ||
| + | |||
| + | == constructors and destructors case == | ||
| + | |||
| + | [[Constructor|<syntaxhighlight lang="pascal" enclose="none">Constructor</syntaxhighlight>]], example 1 : | ||
| + | <syntaxhighlight> | ||
| + | ... | ||
| + | TTest.Create; | ||
| + | begin | ||
| + | Inherited; // Always at the beginning of the constructors and start the constructor (code only) of the parent class | ||
| + | ... | ||
| + | end; | ||
| + | </syntaxhighlight> | ||
| + | |||
| + | <syntaxhighlight lang="pascal" enclose="none">Constructor</syntaxhighlight>, example 2 : | ||
| + | <syntaxhighlight> | ||
| + | ... | ||
| + | TTest.Create(...); | ||
| + | begin | ||
| + | Inherited Create(...); // Always at the beginning of the constructors and start the constructor (code only) of the parent class | ||
| + | ... | ||
| + | end; | ||
| + | ... | ||
| + | </syntaxhighlight> | ||
| + | |||
| + | [[Destructor|<syntaxhighlight lang="pascal" enclose="none">Destructor</syntaxhighlight>]], example 3 : | ||
| + | <syntaxhighlight> | ||
| + | TTest.Destroy; | ||
| + | begin | ||
| + | ... | ||
| + | Inherited; // Always at the end of the destructors and start the destructor (code only) of the parent class | ||
| + | end; | ||
| + | ... | ||
</syntaxhighlight> | </syntaxhighlight> | ||
Revision as of 20:37, 29 March 2019
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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;
...