Is Delphi “with” keyword a bad practice?

by

The biggest danger of with, outside of pathological conditions like “with A, B, C, D” is that your code can silently change meaning with no notice to you. Consider this example:

with TFoo.Create
try
  Bar := Baz;
  DoSomething();
finally
  Free;
end;

You write this code knowing that Bar is a property of TFoo, and Baz is a property of the type containing the method which has this code.

Now, two years later, some well-meaning developer comes in adds a Baz property to TFoo. Your code has silently changed meaning. The compiler won’t complain, but the code is now broken.

More Related Contents:

  1. Why should I not use “with” in Delphi?
  2. Why should I not use “if Assigned()” before accessing objects?
  3. Why cannot take address to a nested local function in 64 bit Delphi?
  4. Debugging Access Violation errors?
  5. How to dynamically create controls aligned to the top but after other aligned controls?
  6. Getting output from a shell/dos app into a Delphi app
  7. How to define application version in one place for multiple applications?
  8. What’s the simplest way to call Http GET url using Delphi?
  9. Binary to Base64 (Delphi)
  10. How do I translate a C union into Delphi?
  11. How to add mouse wheel support to a component descended from TGraphicControl?
  12. How do I make a PNG resource?
  13. TThreadedQueue not capable of multiple consumers?
  14. Why can Delphi DLLs use WideString without using ShareMem?
  15. How do I run a command-line program in Delphi?
  16. Should the compiler hint/warn when passing object instances directly as const interface parameters?
  17. Delphi – get what files are opened by an application
  18. How can I display Crystal XI reports inside a Delphi 2007 application?
  19. My program never releases the memory back. Why?
  20. Patch routine call in delphi
  21. How to efficiently rotate bitmaps in code
  22. Component Creation – Joining Components Together?
  23. Modifying or deleting a line from a text file the low-level way?
  24. How to disable VCL styles in Delphi
  25. DecimalSeparator in SysUtils and System.SysUtils
  26. Resize PNG image
  27. Delphi control that could mimic “Add-ons|Extension list” of Firefox?
  28. How can I make AllocateHwnd threadsafe?
  29. Can 48×48 or 64×64 icons be obtained from the Vista Shell?
  30. How to cast a Interface to a Object in Delphi

Leave a Comment