To implement a registry watcher in Delphi, you will need to use the TRegistry class, which is part of the Registry unit. This class provides methods and properties that allow you to access and manipulate the Windows registry.
Here is an example of how you might use the TRegistry class to implement a registry watcher in Delphi:
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uses Registry; var Registry: TRegistry; begin // Create a new TRegistry instance Registry := TRegistry.Create; // Set the registry root key Registry.RootKey := HKEY_LOCAL_MACHINE; // Open the registry key Registry.OpenKey(‘SOFTWARE\MyApplication’, True); // Check the value of a registry key if Registry.ValueExists(‘Version’) then WriteLn(‘Version: ‘, Registry.ReadString(‘Version’)); // Set the value of a registry key Registry.WriteString(‘Version’, ‘1.0.0’); // Close the registry key Registry.CloseKey; // Free the TRegistry instance Registry.Free; end; |
In this example, we create a new TRegistry instance and open a registry key. We then check the value of a registry key and set its value, and finally close the registry key and free the TRegistry instance.
To implement a registry watcher, you will need to use the OnChange event of the TRegistry class, which is fired whenever the registry key that the TRegistry instance is currently opened to is changed. You can use this event to monitor changes to the registry key and take appropriate action when it changes. Here is an example of how you might use the OnChange event to implement a registry watcher:
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uses Registry; var Registry: TRegistry; begin // Create a new TRegistry instance Registry := TRegistry.Create; // Set the registry root key Registry.RootKey := HKEY_LOCAL_MACHINE; // Open the registry key Registry.OpenKey(‘SOFTWARE\MyApplication’, True); // Set the OnChange event handler Registry.OnChange := RegistryChanged; // … // Event handler for the OnChange event procedure RegistryChanged(Sender: TObject); begin // Check the value of a registry key if Registry.ValueExists(‘Version’) then WriteLn(‘Version changed: ‘, Registry.ReadString(‘Version’)); end; end; |
In this example, we create a new TRegistry instance, open a registry key, and set the OnChange event handler. When the OnChange event is fired, the RegistryChanged event handler is called, which checks the value of a registry key and takes appropriate action when it changes.
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