Object Lifetime Management

In Delphi, there are several levels of object lifetime management.

Delphi takes care of the design-time objects like components and controls on a form. It will also automatically release any auto-created form.

However, any dynamic object created in code is the responsibility of the developer. If using interfaces with reference counting, it is not necessary to explicitly release the variables. But the developer will be responsible for releasing any other variable. If the developer fails to dispose of these variables, it will create memory leaks which may exhaust the server memory and crash the application over time.

A typical syntax for creating dynamic objects with a short lifetime is creating and disposing them in a try..finally block.

Delphi example

F := TFileStream.Create('NewFile.bin', fmCreate);

try
  F.Write(Buffer, 1024)
finally
  F.Free; // dispose object when it is done
end;

The file stream object will be freed when the try..finally block is executed. This principle must be followed when creating dynamic objects with a short lifetime.