Code example: Do you really know Delphi well?

Code example: Do you really know Delphi well?

PRocedure StepEditor( strgrid: TStringGrid; Step: TStep );

var

sValue, sField: string;

EditorClass: TStepEditorClass;

Editor: TStepEditor;

begin

sField := strgrid.Cells[0, strgrid.Selection.Top];

sValue := strgrid.Cells[1, strgrid.Selection.Top];

EditorClass := EditorClassList.Editors[ sField ];

Editor := EditorClass.Create;

Editor.Field := sField;

Editor.Step := Step;

Editor.Edit(sValue);

Editor.Free;

strgrid.Cells[ 1, strgrid.Selection.Top ] := sValue;

end;

EditorClass is a Class of Class, that is, a class of classes

for example

TFormClass = Class of TForm;

But it is different from: TFormClass = Class(TForm); These are two concepts!

The EditorClassList stores a list of classes;

Editor := EditorClass.Create;

Create is a class method, not an object method, so an instance of EditorClass can be created from EditorClass

Replenish:

TStepEditor = Class( TObject )

...

End;

TStepEditorClass = Class of TStepEditor;

Why can Object Inspector provide a convenient editing environment?

Why do different fields have different values ​​for selection, different verification methods, and pop-up edit boxes?

no the same? Because different property editors are registered according to different field types;

Simplifying the function of registering the property editor provided by Delphi can be described as follows:

RegisteryPropertyEditor( PropertyFieldType, EditorClass );

^Here is the type name, such as Bool, Integer, ...etc.

^Here is the class name of the corresponding editor. Note that it is not the character description of the class name.

When actually running, when the user clicks a field in the Object Inspector,

Delphi internally searches for the editor class corresponding to the field type; then creates an instance of the class from the found class;

Perform related operations (deciding whether there is a drop-down box, whether there is a button, etc.)

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