The Wiert Corner – irregular stream of stuff

Jeroen W. Pluimers on .NET, C#, Delphi, databases, and personal interests

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Archive for the ‘Software Development’ Category

Tip for the doc team: make TMonitor.Enter docs more clear on non-blocking re-entry from the same thread

Posted by jpluimers on 2018/04/19

Even when the Delphi team was large, the documentation was lacking, so with the reduced Delphi team size, I don’t have high expectations of the below to get fixed.

But since much of the post Delphi 7 run-time library looks a lot like the .NET core, you can usually fallback to the Microsoft documentation.

Tip for the doc team: make http://docwiki.embarcadero.com/Libraries/en/System.TMonitor.Enter more clear. Especially that if the same thread calls TMonitor.Enter more than one time, it will allow entry without blocking as per System.Threading.Monitor.Enter Method (Object) documentation https://msdn.microsoft.com/en-us/library/de0542zz

(note that this got introduced in Delphi XE3: http://docwiki.embarcadero.com/Libraries/XE3/en/System.TMonitor.Enter)

–jeroen

via: [WayBack] Tip for the doc team: make http://docwiki.embarcadero.com/Libraries/Seattle/e…

Posted in Delphi, Delphi 10 Seattle, Delphi 10.1 Berlin (BigBen), Delphi XE3, Delphi XE4, Delphi XE5, Delphi XE6, Delphi XE7, Delphi XE8, Development, Software Development | 2 Comments »

Reminder to Self: `TProc` is incompatible with parameterless procedures on interfaces

Posted by jpluimers on 2018/04/19

I knew that methods on interfaces were not compatible with the procedure of object (like [WayBack] TProc)or function of object construct, but they are also not compatible with the reference to procedure or reference to function construct.

Via: [WayBack] I try to call an Interface method from TThread.Syncrhonize()…and Berlin don’t accept that… – Paul TOTH – Google+

If you want it fixed, vote for [RSP-13007] Interface methods are not assignable to anonymous method variable – Embarcadero Technologies (Thanks Stefan Glienke).

You can work around it with an anonymous method.

This won’t work:

program Project1;
{$APPTYPE CONSOLE}
uses
  SysUtils;
 
type
  ITest = interface
    ['{B5AD87E8-A3DF-4B83-BE14-997C2E76A06C}']
    procedure Run;
  end;
 
  TTest = class(TInterfacedObject, ITest)
    procedure Run;
  end;
 
procedure TTest.Run;
begin
  Writeln('PASS')
end;
 
var
  test: ITest; // <- change this to TTest and it compiles
  proc: TProc;
begin
  test := TTest.Create;
  proc := procedure begin test.Run; end; // <- this compiles
  proc := test.Run; // E2010 Incompatible types: 'TProc' and 'procedure, untyped pointer or untyped parameter'
  proc();
  Readln;
end.

–jeroen

 

Posted in Delphi, Delphi 10 Seattle, Delphi 10.1 Berlin (BigBen), Delphi XE, Delphi XE2, Delphi XE3, Delphi XE4, Delphi XE5, Delphi XE6, Delphi XE7, Delphi XE8, Development, Software Development | Leave a Comment »

… / source / Native / Delphi / Library / Data / DataSetEnumeratorUnit.pas — Bitbucket

Posted by jpluimers on 2018/04/18

Reminder to self that I one day need to write more about this enumerator:

[WayBackjeroenp / BeSharp.net / source / Native / Delphi / Library / Data / DataSetEnumeratorUnit.pas — Bitbucket

It’s not nearly as good as the one by Uwe Raabe, but I didn’t really update this code for about a decade as it has functioned well for me in the current state: in 2009 it was like [WayBackbo library – Source Code.

Code by Uwe is at [WayBackDataset Enumerator Reloaded | The Art of Delphi Programming via [WayBack] Refurbishing old code: http://www.uweraabe.de/Blog/2017/02/09/dataset-enumerator-reloaded/Uwe Raabe – Google+

A couple of years ago I wrote a two-part article about a dataset enumerator: A Magical Gathering – Part 1 and Part 2. Well, things evolved a bit since then and I wondered how one would implement something similar given the current features of Delphi. Actually I am following here a suggestion from commenter Alan Clark.

So for now it’s just to document that my enumerator is there and that it works as intended.

I referenced an older version at [WayBackFor-in Enumeration – ADUG as I used it at Spoken @ CodeRage III, December 1-5, 2008 on Delphi, database and XML related topics and Source: Conferences/2009/DelphiLive.2009/Smarter-code-with-databases-and-data-aware-controls.

A small video on how you use it is here:

It was back when Better Office and CodeGear still existed and we celebrated (late) Gwan Tan’s 50th birthday.

O the days (:

More history:

–jeroen

Posted in Delphi, Delphi 10 Seattle, Delphi 10.1 Berlin (BigBen), Delphi 2007, Delphi 2009, Delphi 2010, Delphi XE, Delphi XE2, Delphi XE3, Delphi XE4, Delphi XE5, Delphi XE6, Delphi XE7, Delphi XE8, Development, Software Development | 2 Comments »

TTemporaryFileStream – via DELPHI AREA » How to have a temporary stream, with no size limit

Posted by jpluimers on 2018/04/17

I needed a TTemporaryFileStream and found it at [WayBackDELPHI AREA » How to have a temporary stream, with no size limit.

It taught me that CreateFileA and CreateFileW (the ANSI and Unicode versions of[WayBackCreateFile function (Windows)) accept a FILE_FLAG_DELETE_ON_CLOSE parameter, so as soon as you close the handle, Windows will dispose of the file.

Note however that this will apply to the file handle so if you want to open it multiple times, you need [WayBackDuplicateHandle function (Windows) as per [Archive.isThe FILE_FLAG_DELETE_ON_CLOSE flag applies to the handle, also known as the file object, which is not the same as the file – The Old New Thing

–jeroen

Posted in Delphi, Development, Software Development | Leave a Comment »

Why you should try to avoid using Variant operations in Delphi

Posted by jpluimers on 2018/04/17

[WayBackDelphi “WAT?!” of the day: var v1, v2: Variant; begin v1 := True; v2 := True… shows some interesting code.

The [WayBackVariant Types (Delphi) – RAD Studio: Variant Type Conversions (and the decimal point/comma handling or rounding issues not documented there) usually kill you and are the most important reason to avoid Variant operations in Delphi.

–jeroen

Posted in Delphi, Development, Software Development | 5 Comments »

 
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