Hi All,

I have a TObjectList that contains many objects that have a property called "Position" which is an integer.

Could somebody show me an example of the code that I will need to create that will sort all of my Objects within the TObjectList so that they are in position order e.g. 1,2,3,4,5 and so on?

Thanks

Richard
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Call TList.Sort method and supply a comparison function.

For example:

List.Sort(@CompareByPositionPtr);
function CompareByPosition(A, B: TMyObject): Integer; inline;
begin
  if A.Position < B.Position then
    Result := -1
  else if A.Position > B.Position then
    Result := 1
  else
    Result := 0;
end;
function CompareByPositionPtr(A, B: Pointer): Integer;
begin
  Result := CompareByPosition(TMyObject(A), TMyObject(B));
end;

This kind of question is better suited on the forum I think

Denis
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Denis Kozlov wrote

This kind of question is better suited on the forum I think

Why? This mailing list is just as much a support area as the web forum. Not everybody likes web based forums (I don't).

Granted the question related more to the RTL that Lazarus or LCL, so if anything, it could have been posted in the fpc-users mailing list. But you were kind enough to answer anyway. ;-)

Regards,
Graeme

Forum is especially good for tutorials, generic and commonly asked questions - like a repository of knowledge, Also, forums are more easily searched, indexed by search engines and easier to view for novice users. Hence, I think this question/answer would reach more end users while being on the forum, instead of on a mailing list.

Denis
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Denis Kozlov wrote

Also, forums are more easily searched, indexed by search engines and easier to view for novice users.

Lets agree to disagree. ;-)

ps:
The mailing lists are also searched and indexed by search engines - thanks to services like Nabble and many others. But then again, my email client does just fine searching on its own (and can do it offline).

http://free-pascal-lazarus.989080.n3.nabble.com/
http://free-pascal-general.1045716.n5.nabble.com/

Regards,
Graeme

Hi Denis,

Thanks for your reply.

?Would I call the List.sort externally, or would the List call sort when an Add has happened, as I don't seem to have a ".sort" method on my TObjectList?

Thanks?

?Richard?
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Richard Mace wrote

?Would I call the List.sort externally, or would the List call sort when an Add has happened, as I don't seem to have a ".sort" method on my TObjectList?

You need to call List.Sort yourself, it is not sorted automatically when you add more elements.

TObjectList does have a Sort method, since it descends from TList class.

Denis
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Thanks Denis,

I am now getting:

inboundroutedestlist.pas(49,35) Error: Incompatible type for arg no. 1: Got "<procedure variable type of function(Pointer;Pointer):LongInt of object;Register>", expected "<procedure variable type of function(Pointer;Pointer):LongInt;Register>"

Any ideas?

Richard

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You are using "procedure of object" where you need "procedure".

(One solution is to add static keyword to your procedure declaration, if the FPC version you use supports the typecast - iirc, fpc 3.0.0 can't do that in objfpc mode.)

Ondrej

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Ondrej Pokorny wrote

You are using "procedure of object" where you need "procedure".

?Thanks Ondrej, that sorted it :)
?
?Thanks for everyone's help?

Richard
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