When you use the Delphi for .NET compiler, and you get this message: “E2029 identifier expected but 'xxx' found ” error message, what you need to fix this bug is just insert the ampersand (&) character before the 'xxx' identifier. The ampersand (&) character is also known as the escape character in Delphi for .NET compilers.
In 2017, with the release of Delphi 10.2 Tokyo, Embarcadero introduced a specialized implementation of the Observer pattern into the System.Classes unit. While it has been in the wild for 9 years, it remains a "hidden" architecture for many, primarily because it serves as the invisible engine behind LiveBindings. Other than live bindings, you can also use the Observer pattern as a way to update component settings to the Windows registry, an .ini file, or persist it elsewhere.
System.Classes