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 ‘Delphi 2006’ Category

.NET/C#/VB.net: some links on ExpandoObject

Posted by jpluimers on 2013/10/10

Still a C# 4.0 / .NET 4 feature that I need to investigate more deeply: ExpandoObject, partially because I had very bad memories of Variant support in Delphi.

So here are a few links.

First of all: since VB.NET already does late binding with the Object keyword, you cannot use ExpandoObject with Strict On in VB.NET 10.0 and up:

Now the C# links:

–jeroen

Posted in .NET, .NET 4.0, .NET 4.5, C#, C# 4.0, C# 5.0, Delphi, Delphi 2005, Delphi 2006, Delphi 2007, Delphi 2009, Delphi 2010, Delphi 3, Delphi 4, Delphi 5, Delphi 6, Delphi 7, Delphi XE, Delphi XE2, Delphi XE3, Development, Software Development | 5 Comments »

Delphi virtual constructors: example of the “Factory” design pattern (via: Stack Overflow)

Posted by jpluimers on 2013/07/18

I bumped into the below answer that I gave a while (what is 4 years in a developer’s life ) on StackOverflow.

It is about Delphi Design Patterns. Sepcifically the Factory Pattern, and explains how virtual constructors implement it.

They are one of the 3 corner stones on which the component based Delphi form designer and object inspector are built:

  • Virtual constructors
  • Properties (events are just a special form of property)
  • Run-Time Type Information.

So here it goes: Read the rest of this entry »

Posted in Delphi, Delphi 1, Delphi 2, Delphi 2005, Delphi 2006, Delphi 2007, Delphi 2009, Delphi 2010, Delphi 3, Delphi 4, Delphi 5, Delphi 6, Delphi 7, Delphi 8, Delphi XE, Delphi XE2, Delphi XE3, Delphi XE4, Development, Software Development | 6 Comments »

2D transformations as answer to “delphi – Change orientation of a shape” – Stack Overflow

Posted by jpluimers on 2013/07/09

Sometimes a generic answer to a specific answer gives people a lot more insight into what they actually want to accomplish than a specific answer.

Plus that the knowledge does not only apply to VCL in any Delphi version: it works in any development environment where you can draw.

That’s why I like this 2D transformation answer so much: Read the rest of this entry »

Posted in Delphi, Delphi 1, Delphi 2, Delphi 2005, Delphi 2006, Delphi 2007, Delphi 2009, Delphi 2010, Delphi 3, Delphi 4, Delphi 5, Delphi 6, Delphi 7, Delphi x64, Delphi XE, Delphi XE2, Delphi XE3, Delphi XE4, Development, Software Development | Leave a Comment »

Crap: the outsourcing party of the client wrote C-code like this in 2005, and nobody scrutinized it

Posted by jpluimers on 2013/06/12

I was involved in a big project migrating a complex stack from Windows XP to Windows 7 x86, and got scared this !@#$ out of me.

The stack communicated to WebSphere MQ on AS/400 from Windows, and on the Windows side of things consisted of a UI developed in in Cool:Gen, a C interface to a Delphi DLL, which takes care of the communication to WebSphere MQ.

Digression:

This all was histerically grown. In the beginning (early to mid 90s last century) it was a big Borland Pascal/Turbo Pascal application – running on DOS, Windows 3.1x, Windows 95 and OS/2 2.x/3.0 – that talked over a propriatary layer over SNA to AS/400.
The vendor of that layer didn’t respond to a request for Windows NT 4.x compatibility, and meanwhile some client applications were about to be developed in Delphi.

So in 1997/1998 – together with a great AS/400 software developer – I wrote a SNA based APPC/CPI-C communication layer in Delphi 3 that could be accessed from both Turbo Pascal (using a file based interface) and Delphi (using an object interface).
The DOS interface was an executable around the Delphi interface, which was a set of classes.

Delphi part

The Delphi part of the DOS interface was centered around FindFirstChangeNotification/CreateProcess combined with MsgWaitForMultipleObjects/WaitForSingleObject to make the waiting as efficient as possible.

DOS part

DOS part

The DOS part of the Delphi interface was centered around this piece to make waiting efficient:

asm
  int $28
  mov ax, $1000
  int $15 { DESQview/TopView give up time slice }
  mov ax, $1680
  int $2F
end;

Thanks to the RBIL: Ralf Brown’s Interrupt List (there are now multiple HTML versions of it), it makes use of these tricks so DOS applications can efficiently wait : Read the rest of this entry »

Posted in C, CVS, Delphi, Delphi 2006, Delphi 3, Delphi 5, Delphi XE2, Development, Dimensions CM by Serena, MKS Integrity, Software Development, Source Code Management | 3 Comments »

Run batch file from Delphi IDE (via: Stack Overflow)

Posted by jpluimers on 2013/05/29

In pre-Galileo versions of Delphi it was easy to run a .BAT or .CMD file as a main project file: just press F9.

Thanks to iManBiglary for posting how to do this in modern Delphi versions. Paraphrased:

Add the file path to cmd.exe (easieist is to add $(ComSpec) which expands the %ComSpec% environment variable) in the tools menu, with /c$EDNAME as the parameter.
In addition, you can tell the IDE to save your file before running the external tool with the $SAVE macro

One of the things you can do with this is add a project containing a batch file that starts to assemble your build results to create a deployment set.

–jeroen

via: Run batch file from Delphi IDE – Stack Overflow.

Posted in Delphi, Delphi 2005, Delphi 2006, Delphi 2007, Delphi 2009, Delphi 2010, Delphi XE, Delphi XE2, Delphi XE3, Development, Software Development | Leave a Comment »

Don’t pass interfaces between application architectures over a DLL boundary

Posted by jpluimers on 2013/05/15

It is unwise to pass objects allocated in one framework over a DLL boundary to a different framework.

In the case of Using C dll in delphi return nothing, someone tries to pass an Interface to some memory in the C side over to Delphi.

Unless that interface is COM based, don’t do that!

In a more general way: don’t pass memory allocated on the DLL side over to the client side, no matter what kind of client you have.

From the DLL, either pass simple types, or fill buffers allocated at the client side.

Edit:

There was a nice Delphi DLL return string from C# … .NET 4.5 Heap Corruption but .NET 4.0 works? Explain please? – Stack Overflow question explaining in detail what to do for strings in a specific case: use the COM heap on the Delphi side using CoTaskMemAlloc (actually it uses the OLE task memory allocator as the Old New Thing explains).

–jeroen

via: Using C dll in delphi return nothing – Stack Overflow.

Posted in .NET, .NET 2.0, .NET 3.0, .NET 3.5, .NET 4.0, .NET 4.5, Delphi, Delphi 1, Delphi 2005, Delphi 2006, Delphi 2007, Delphi 2009, Delphi 2010, Delphi 3, Delphi 4, Delphi 5, Delphi 6, Delphi 7, Delphi 8, Delphi x64, Delphi XE, Delphi XE2, Delphi XE3, Development, Software Development | 5 Comments »

Delphi static class methods are assignment compatible with plain old function pointers

Posted by jpluimers on 2013/04/24

So I won’t forget, as the  [WayBackstatic in different languages varies in meaning:

[WayBack] Static on class methods makes them assignment compatible with plain old function pointers.

Thanks Moritz Beutel for initially posting this.

–jeroen

via:

related:

  • [Archive.isFacebook – Delphi developer: static class methods
  • [WayBack] Delphi 2007: Methods; Class Methods:

    Like class methods, class static methods can be accessed without an object reference. Unlike ordinary class methods, class static methods have no Self parameter at all. They also cannot access any instance members. (They still have access to class fields, class properties, and class methods.) Also unlike class methods, class static methods cannot be declared virtual.

    Methods are made class static by appending the word static to their declaration.

Posted in Delphi, Delphi 2005, Delphi 2006, Delphi 2007, Delphi 2009, Delphi 2010, Delphi XE, Delphi XE2, Delphi XE3, Development, Software Development | 5 Comments »

Delphi + ADO + dBase – Stack Overflow

Posted by jpluimers on 2013/04/10

For my research queue:

I should look at the below ConnectionStrings to access dBase with ADO from Delphi, If I ever need to do that.

Thanks Cromulent for asking, Nelson for editing and Pieter for answering:

Microsoft dBase ODBC driver

Driver={Microsoft dBASE Driver (*.dbf)};DriverID=277;OLE DB Services = -1;Extended Properties=dBase IV;Dbq=c:\mypath

doing operations like ADOTable1.Open are very fast (good) but GetIndexNames returns nothing (bad).

Microsoft Jet OLEDB 4.0 driver

Provider=Microsoft.Jet.OLEDB.4.0;Extended Properties=dBASE IV;OLE DB Services=-1;Data Source=c:\mypath

doing operations like ADOTable1.Open are exceedingly slow (bad) while GetIndexNames does return index names the way it should (good).

How do I get both speed and the index info via ADO for the dBase tables?

Microsoft Paradox Driver 7.x

“We use the following connection string which works really well.”

Provider=MSDASQL.1;Persist Security Info=False;Extended Properties="Driver={Microsoft Visual FoxPro Driver};UID=;SourceDB=c:\mypath;SourceType=DBF;Exclusive=No;BackgroundFetch=Yes;Collate=Machine;Null=Yes;Deleted=Yes;"

–jeroen

via Delphi + ADO + dBase – Stack Overflow.

Posted in Delphi, Delphi 2005, Delphi 2006, Delphi 2007, Delphi 2009, Delphi 2010, Delphi 5, Delphi 6, Delphi 7, Delphi XE, Delphi XE2, Delphi XE3, Development, Software Development | 8 Comments »

autoscrolling memo in delphi – Stack Overflow

Posted by jpluimers on 2013/04/03

Just found this great answer by vcldeveloper to autoscroll a readonly logging memo in Delphi which works from Delphi 1 and up (:

For such a simple task, you don’t need to buy a commercial component! All you need to do is to send an EM_LINESCROLL message to that memo control, to make it scroll to the last line:

procedure ScrollToLastLine(Memo: TMemo);
begin
  SendMessage(Memo.Handle, EM_LINESCROLL, 0,Memo.Lines.Count);
end;

If your memo is read-only to users and is updated automatically by the application, you can put a call to the above procedure in its OnChange event-handler, so that whenever the text inside the memo is changed, it is automatically scrolled down to the last line.

–jeroen

via: autoscrolling memo in delphi – Stack Overflow.

Posted in Delphi, Delphi 1, Delphi 2005, Delphi 2006, Delphi 2007, Delphi 2009, Delphi 2010, Delphi 3, Delphi 4, Delphi 5, Delphi 6, Delphi 7, Delphi x64, Delphi XE, Delphi XE2, Delphi XE3, Development, Software Development | 9 Comments »

Delphi: you should avoid the `with` statement as it makes your code less future proof

Posted by jpluimers on 2013/03/27

As I wrote before, I’m with the [WayBack] Delphi with haters camp, and this is why:

Using the [WayBackwith statement in Delphi makes your code less future proof.

Originally, the with statement in Pascal was argumented in part of allowing compiler optimisations:

PASCAL User Manual and Report – Kathleen Jensen, Niklaus Wirth – Google Books

The with clause effectively opens the scope containing field identifiers of the specified record variable, so that the field identifiers may occur as variable identifiers. (Thereby providing an opportunity for the compiler to optimize the qualified statement.)

Screenshots of this 1975 book are below the fold.

The Delphi (actually even before that Turbo Pascal compiler) has no measurable difference between with and non-with code.

The debugger however, still does not support with, and there are other drawbacks of which one is below.

The below code example is just one of many. I show it because I recently bumped into doing some long overdue code porting to Delphi XE3.

Since I’ve been bitten by using with a couple of times before, it didn’t take me long to find the cause.

Example code where FIConData is of type NOTIFYICONDATAW that used to compile fine:

    with FIconData do
    begin
      cbSize := SizeOf(FIconData);
      Wnd := Self.Handle;
      uID := $DEDB;
      uFlags := NIF_MESSAGE or NIF_ICON or NIF_TIP;
      hIcon := Application.Icon.Handle;
      uCallbackMessage := WM_CAS400NTIcon;
      StrCopy(szTip, PChar(Caption));
    end;

Well, as of Compiler Version 20, it doesn’t compile any more. Read the rest of this entry »

Posted in Borland Pascal, Conference Topics, Conferences, Delphi, Delphi 1, Delphi 2005, Delphi 2006, Delphi 2007, Delphi 2009, Delphi 2010, Delphi 3, Delphi 4, Delphi 5, Delphi 6, Delphi 7, Delphi XE, Delphi XE2, Delphi XE3, Development, Event, Pascal, Software Development, Turbo Pascal, With statement | 32 Comments »