Как присвоить все значения полей одного класса, другому такому же классу

Delphi , Компоненты и Классы , RTTI

Автор: Serge Gubenko

How can I assign all property values (or if it's not possible only published property values, or some of them) of one class (TComponent) to another instance of the same class? What I want to do is:

MyComponent1. {property1} := MyComponent2. {property1};
{...}
MyComponent2. {propertyN} := MyComponent2. {propertyN};

Is there a better and shorter way to do this? I tried this: MyComponent1 := MyComponent2; But it doesn't work. Why not? Can I point to the second component ?

MyComponent2 and MyComponent1 are pointers to your components, and this kind of assigment leads to MyComponent1 pointing to MyComponent2. But it will not copy its property values.

A better way is to override the assign method of your control, do all property assignment there and call it when you need to copy component attributes. Here's example:

procedure TMyComponent.Assign(Source: TPersistent);
begin
  if Source is TMyComponent then
  begin
    property1 := TMyComponent(Source).property1;
    { ... }
  end
  else
    inherited Assign(Source);
end;

To assign properties you'll need to set this line in the code:

MyComponent1.Assign(MyComponent2); 

Статья Как присвоить все значения полей одного класса, другому такому же классу раздела Компоненты и Классы RTTI может быть полезна для разработчиков на Delphi и FreePascal.

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