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#1 Re: Other components » Memory corruption bug in TDynArray.AddArray ? » 2013-07-04 01:51:40

Dangph

Thanks, but that doesn't seem to have fixed the problem.

I'm thinking that the Delphi 2007 compiler has bugs when it comes to returning dynamic arrays from recursive functions.

I saw something like this happen:

function SomeFunc: TSomeArray;
begin
  // ...   <-------------
  result := SomeFunc;
end;

(That's plain Delphi code, nothing to do with TDynArray.)

At the indicated line, result retained its value from the previous iteration. It wasn't initialized. I think that a reference-counted local variable should be automatically initialized by the compiler. The fact that it wasn't suggests that the compiler has problems dealing with that case.

#2 Re: Other components » Memory corruption bug in TDynArray.AddArray ? » 2013-07-01 23:49:55

Dangph

If I change the code as follows, then it works as expected. The changed lines are the ones marked.

function recurse(i: integer): TRecArray;
var
  dyn: TDynArray;
  rec: TRec;
  childVals: TRecArray;
begin
  dyn.Init(TypeInfo(TRecArray), result);
  rec.Val1 := Format('This is Val1: %d', [i]);
  rec.Val2 := Format('This is Val2: %d', [i]);
  dyn.Add(rec);

  if i > 0 then
  begin
    childVals := recurse(i - 1);
    //dyn.AddArray(childVals);    // <-------
    for rec in childVals do       // <-------
      dyn.Add(rec);               // <-------
  end;
end;

#3 Re: synopse.info » New "Downloads" page and button » 2013-07-01 12:45:26

Dangph

Merci. TDynArray est une classe très sympa. Elle va vraiment me simplifier la vie. Je vous ai donné un petit don.

#4 Other components » Memory corruption bug in TDynArray.AddArray ? » 2013-07-01 11:54:01

Dangph
Replies: 4

Consider this program:

program Project49;

{$APPTYPE CONSOLE}

uses
  SysUtils, SynCommons;

type
  TRec = packed record
    val1: string;
    val2: string;
  end;

  TRecArray = array of TRec;

function recurse(i: integer): TRecArray;
var
  dyn: TDynArray;
  rec: TRec;
  childVals: TRecArray;
begin
  dyn.Init(TypeInfo(TRecArray), result);
  rec.Val1 := Format('This is Val1: %d', [i]);
  rec.Val2 := Format('This is Val2: %d', [i]);
  dyn.Add(rec);

  if i > 0 then
  begin
    childVals := recurse(i - 1);
    dyn.AddArray(childVals);
  end;
end;

var
  recs: TRecArray;
  rec: TRec;
begin
  recs := recurse(10);

  for rec in recs do
  begin
    WriteLn(rec.Val1);
    WriteLn(rec.Val2);
  end;
end.

I would expect to see this output:

This is Val1: 10
This is Val2: 10
This is Val1: 9
This is Val2: 9
This is Val1: 8
This is Val2: 8
This is Val1: 7
This is Val2: 7
This is Val1: 6
This is Val2: 6
This is Val1: 5
This is Val2: 5
This is Val1: 4
This is Val2: 4
This is Val1: 3
This is Val2: 3
This is Val1: 2
This is Val2: 2
This is Val1: 1
This is Val2: 1
This is Val1: 0
This is Val2: 0

But instead I see this:

This is Val1: 10
This is Val2: 10
This is Val1: 9
This is Val2: 9
This is Val1: 8
This is Val2: 8
This is Val1: 7
This is Val2: 7
This is Val1: 6
This is Val2: 6
This is Val1: 5
This is Val2: 5

(There are some blank lines at the end, but FluxBB has chopped them.) The last 5 records in the array contain empty strings. Is this a memory corruption bug?

I am using Delphi 2007, and the latest version of SynCommons.

#5 Re: synopse.info » New "Downloads" page and button » 2013-07-01 05:02:27

Dangph

Hello

If I want to get TDynArray, is it better to download mORMot and grab the files out of there, or is it better to download the files individually?

If I try to download synopse.inc, I get a "403 Fobidden" error: http://synopse.info/fossil/raw/Synopse. … 29dc18f480

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