Wednesday, 19 April 2017

Only use ShowMessage() function for debugging

I always use the ShowMessage function for debugging while doing development and always exclude it from release code for the following reasons:


  1. MessageDlg or MessageBox functions are much better as a popup dialog than ShowMessage, they have more options and the presentation is better giving the user a visual icon categorising the meaning of the popup.
  2. It is easy to search through all the code and check there is no 'ShowMessage' operational before checking in the code. I had a customer call me once saying they have a popup (ShowMessage) which just says 'Hello', this was because the developer forgot to remove or comment out the ShowMessage before checking in.
  3. Because there is no icon with a ShowMessage, some testers and end users assume the popup is an error dialog. I have had the same but to a lesser extent with MessageDlg, the icon helps to show when it is information, warning or confirmation.
Some developers seem to use ShowMessage to quickly display information to the user, they are using ShowMessage because they think it is quicker to use, but in GExperts there is a Message Dialog tool that creates the code based on the options the developer sets.

There is the argument not to use these popup at all, and in some applications they cause issues. I think that popups can be annoying to the user if used too much, but I do not have a problem with them if they are used sparingly and they do not cause problems with the operation of the application.

I imagine some developers might say you should never use ShowMessage to debug and use breakpoints while debugging, which in most cases is the true, but there are occasions when some testing by the developer might be done in a non-development environment, in which case you cannot use the debugger. 

Wednesday, 15 March 2017

Why are semi-colons sometimes not required?

Over the 20 years I've been developing commercial software one question I still have with the Delphi language is why was the language designed so semi-colons are not required at the end of methods? For example:

function DoSomething: boolean;
begin
  if FDoSomethingElse then
  begin
    DoSomethingElse;
  end
end; 

I believe the reason why the compiler does not complain about this, is because the semi-colon in Delphi is a statement separator and not a terminator. If I modify this function for example:

function DoSomething: boolean;
begin
  if FDoSomethingElse then
  begin
    DoSomethingElse;
  end;
  DoOtherStuff
end;

I obviously need to now add in the semi-colon, but I do not need to add in the semi-colon after 'DoOtherStuff'. I currently cannot see any benefit of leaving the semi-colon out. I would not normally code this way and always add in the semi-colon for 2 reasons:

  1. Adding the semi-colon makes the code more consistent.
  2. It means later on when the code is modified the semi-colon does not have to be added.
I have come across Delphi developers who will not put in the semi-colon if it is not required, but cannot see any real benefit from leaving it out. Maybe I have answered my own question, and that is the semi-colon is a separator and when the language was developed they did not see any pros or cons of just allowing the semi-colon not to be there.


Thursday, 23 February 2017

Strict Private Problem with Code Completion

Some time ago I noticed something annoying in Delphi XE with 'Strict Private' and code completion.

Here is an example:

TMyClass = class(TObject)
strict private

public
    property Test: string read FTest write FTest;
end;

When I do CTRL + Shift + C to add the private member to the class it does the following:

TMyClass = class(TObject)
strict private

private
    FTest: string;

published

public
    property Test: string read FTest write FTest;
end;

It adds FTest to the private section of the class and also adds the published section, which is not what I want, but if I remove 'strict' it does not add the 'published' section. Because of this I develop my classes  as 'private' and then once I have added all the require properties then I add 'strict' if required. I am not sure if this behaviour is some setting somewhere that I am not aware of, or whether this is something that might have changed in more recent versions of Delphi. Is there a valid reason to have a 'published' section when there is a 'strict private' section?

Friday, 27 January 2017

Should constants be uppercase?

In a recent blog someone pointed out to me that boolean values true and false should be uppercase because they are constants. This made me think, usually I put constants in uppercase, however when I code true and false they are always lowercase, so it raises a question about my code style, should all constants be uppercase? If so then true, false and nil should also always be uppercase, but for me this does not look correct. Should constants not be uppercase? One reason why constants are uppercase is so they stand out from variables, but is this the only reason?

When I develop in C#, I follow the recommendation for constants not to be uppercase, so I am starting to feel that maybe this should be the same in Delphi and constants should be camel case for local constants and pascal case for public ones.