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’ Category

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Can we truly assert that an array returned from a function is always a true copy?

Posted by jpluimers on 2020/09/23

The answer is no: [WayBack] Hi all, Can we truly assert that an array returned from a function is always a new true copy and that this is guaranteed to not change in between compil… – Ugochukwu Mmaduekwe – Google+

From Primož book and comment:

Primož Gabrijelčič

Depending on how you create this array.

For example, the following code outputs 42, not 17.

program Project142;

{$APPTYPE CONSOLE}

{$R *.res}

uses
System.SysUtils;

function Bypass(const a: TArray<integer>): TArray<integer>;
begin
Result := a;
end;

var
a, b: TArray<integer>;

begin
SetLength(a, 1);
a[0] := 17;
b := Bypass(a);
a[0] := 42;
Writeln(b[0]);
Readln;
end.

You can use `SetLength(arr, Length(arr))` to make array unique. Changing Bypass to the following code would make the test program emit 17.

function Bypass(const a: TArray<integer>): TArray<integer>;
begin
Result := a;
SetLength(Result, Length(Result));
end;

–jeroen

Posted in Delphi, Development, Software Development | 1 Comment »

Delphi Gem of the day: putting “reintroduce” on a destructor. destructor…

Posted by jpluimers on 2020/09/22

A nice thread with examples of all the things you should not do with the Delphi reintroduce keyword:

[WayBack] Delphi Gem of the day: putting “reintroduce” on a destructor.     destructor Destroy(); reintroduce; overload; In our case all we got was a memory lea… – Moz Le – Google+

The problem is that in the original (archived) documentation, not much waring is given around using reintroduce; it is merely posted as solving a nuisance to absolve a compiler warning.

When using it though, all your alarm systems should go off at their highest level as you break polymorphism, but through careful language usage, the pattern you hide can still be used.

One day I will write a longer blog article on this.

Documentation:

A decade of progress has not changed much on this documentation apart from some nicer formatting:

–jeroen

Posted in Conference Topics, Conferences, Delphi, Development, Event, Software Development | Leave a Comment »

Delphi: TInvokableClassRegistryHelper.GetInterfaceNamespace as the opposite of TInvokableClassRegistry.RegisterInterface

Posted by jpluimers on 2020/09/17

A while ago, I needed the opposite of InvRegistry.RegisterInterface(TypeInfo(MySoapInterfacePortType, 'urn:myURN', 'utf-8');, so instead of registering an interface with a namespace URN, obtain the URN by passing the interface inverting [WayBack] TInvokableClassRegistry.RegisterInterface.

This is the class helper I wrote:

type
  TInvokableClassRegistryHelper = class helper for TInvokableClassRegistry
  public
    function GetInterfaceNamespace(Info: PTypeInfo): string;
  end;

function TInvokableClassRegistryHelper.GetInterfaceNamespace(Info: PTypeInfo): string;
var
  InfoGuid: TGUID;
begin
  // call like `Result := InvRegistry.GetInterfaceNamespace(TypeInfo(MySoapInterfaceType));`
  InfoGuid := GetTypeData(Info)^.Guid; // uses TypInfo; see https://stackoverflow.com/questions/8439246/is-it-possible-to-get-the-value-of-a-guid-on-an-interface-using-rtti
  Result := GetNamespaceByGUID(InfoGuid);
end;

It would have been a lot easier if TInvokableClassRegistry.GetIntfIndex has been public, because then [WayBack]TInvokableClassRegistry.GetRegInterfaceEntry could have been used.

–jeroen

Posted in Conference Topics, Conferences, Delphi, Development, Event, SOAP/WebServices, Software Development | Leave a Comment »

FireDAC can do DBMS back-end conditional SQL via Conditional Substitution

Posted by jpluimers on 2020/09/17

Though the field-types mentioned in the problem and solution are equal (so either is wrong), the solution in [WayBack] I have a little problem with FireDAC and the TStringField and TWideStringField design time generation… – Juan C. Cilleruelo – Google+ pointed out by Jeff Weir is interesting: FireDAC supports conditionals that depend on the DBMS back-end, so you can differentiate between them.

The feature is called Conditional Substitution and has been present ever since AnyDAC (which got bought by Embarcadero, transformed into FireDAC, then after Idera bought Embarcadero, the main developer got pink-slipped).

The AnyDAC documentation is in the wayback machine, though you have to disable the onload event in order to read it.

The [Archive.is] XE5: Preprocessing Command Text (FireDAC) – RAD Studio documentation is not much different from the current state [Archive.is].

More background reading is at [WayBack] www.freepascal.org/~michael/articles/anydac2/anydac2.pdf and Cary Jensen covered it in his 2017 course on FireDAC of which you can see the free ToC.

Example from that thread:

SELECT ART.CD_ITEM                ,
       ART.CD_FAMILY              ,
       ART.CD_CATALOGUE           ,
       CAT.DS_CATALOGUE           ,
       FAM.DS_FAMILY              ,
{IF MSSQL}
       CASE WHEN EXISTS(SELECT 1 FROM CONFIGURATIONS COM WHERE COM.CD_PARENT = ART.CD_ITEM)
          THEN CAST('Y' AS NVARCHAR) 
          ELSE CAST('N' AS NVARCHAR) 
       END HAS_CONFIGURATION      ,
{fi}
{IF FIREBIRD}
       CASE WHEN EXISTS(SELECT 1 FROM CONFIGURATIONS COM WHERE COM.CD_PARENT = ART.CD_ITEM)
          THEN 'Y'  
          ELSE 'N'  
       END HAS_CONFIGURATION      ,
{fi}
       ART.DS_ITEM                ,
       ART.CD_TAX                 ,
       TAX.DS_TAX                 ,
       TAX.PRC_TAX               ,
...

Given the problem statement, the casts likely should have been VARCHAR instead of NVARCHAR, but the construct can be very powerful.

–jeroen

Posted in Database Development, Delphi, Development, Firebird, InterBase, Software Development, SQL, SQL Server | Leave a Comment »

GitHub – gabr42/MultiBuilder: Runs multiple programs in parallel, shows results

Posted by jpluimers on 2020/09/17

Given a Delphi build-VM with enough CPU cores to run many builds in parallel: [WayBack] GitHub – gabr42/MultiBuilder: Runs multiple programs in parallel, shows results.

Much more on this at [WayBack] The Delphi Geek: Introducing MultiBuilder.

Via: [WayBack] Parallel build/test systems made easy(er) – Primož Gabrijelčič – Google+

–jeroen

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

Using Delphi for jiggling the mouse – twm’s blog

Posted by jpluimers on 2020/09/16

To prevent a screen-saver from kicking in [WayBack] jiggling the mouse – twm’s blog:

My solution then is this procedure:

procedure JiggleMouse;
var
  Inpt: TInput;
begin
  Inpt.Itype := INPUT_MOUSE;
  Inpt.mi.dx := 0;
  Inpt.mi.dy := 0;
  Inpt.mi.mouseData := 0;
  Inpt.mi.dwFlags := MOUSEEVENTF_MOVE;
  Inpt.mi.time := 0;
  Inpt.mi.dwExtraInfo := 0;
  SendInput(1, Inpt, SizeOf(Inpt));
end;

Call it in regular intervals and the screen saver will not start.

This is now (or soon will be) in the u_dzOsUtils unit which is part of my dzlib utility library.

–jeroen

Posted in Delphi, Development, Power User, Software Development, Windows | 1 Comment »

Delphi, soap and wrapping values in cdata – Stack Overflow

Posted by jpluimers on 2020/09/15

For my link archive: [WayBack] Delphi, soap and wrapping values in cdata – Stack Overflow

–jeroen

Posted in Delphi, Development, SOAP/WebServices, Software Development, XML/XSD | Leave a Comment »

Reminder to self: iocp-delphi/ThreadPool.pas at master · tondrej/iocp-delphi · GitHub

Posted by jpluimers on 2020/09/15

If I ever need a thread pool in Delphi, then I need to look at this class: [WayBack] iocp-delphi/ThreadPool.pas at master · tondrej/iocp-delphi · GitHub.

Via: [WayBack] Don’t lose time with a known Delphi bug affecting TParallel.Join Don’t lose time with a known Delphi bug affecting TParallel.Join; Ondrej Kelle – Google+

Full repository: [WayBack] GitHub – tondrej/iocp-delphi: Windows I/O Completion Port wrapper class for Delphi and Free Pascal. Wide support too:

  • compilers: Delphi 7 or higher, Free Pascal 3.0.4 or higher
  • targets: Windows XP/Windows Server 2003 or higher, both 32 and 64-bit

–jeroen

Posted in Delphi, Development, Software Development | 1 Comment »

FreePascal downloads I used to get Web Service Toolkit to compile since the Delphi WSDL importer has braindead include support

Posted by jpluimers on 2020/09/11

The Delphi WSDL importer maintenance has been in dormant mode for a long while, which means it still barfs on WSDL include directives.

In the day and age of REST and gRPC, I don’t think it will get any love soon.

Related bug entries are for instance RSP-18630: WSDL generate bad code and RSP-17321: “Import WSDL” generates invalid code without explanation of problem are examples of this, and I’m sure that QC had more if it were still alive; I could find these in the WayBack machine:

The problem manifests itself when the WSDL file includes one or more XSD files. The generated code will contain a section like this:

  // ************************************************************************ //
  // The following types, referred to in the WSDL document are not being represented
  // in this file. They are either aliases[@] of other types represented or were referred
  // to but never[!] declared in the document. The types from the latter category
  // typically map to predefined/known XML or Embarcadero types; however, they could also 
  // indicate incorrect WSDL documents that failed to declare or import a schema type.
  // ************************************************************************ //

Further below is a series of commented out types, all starting with a ! end ending in a column with the namespace of those types.

Searching for the first line gives numerous examples as far back as Delphi 7, for instance:

Based on those, I think the reason is that the WSDL importer fails on <soap:binding transport="http://schemas.xmlsoap.org/soap/http" style="document" /> which is quite common in the real world.

I did not want to pursue manually modifying the WSDL file, or manually generating the types as the WSDL and XSD files were prone to changes and manual steps would make the re-import process more tedious. If you do want to do that, these link might help:

This is what I used to get this to compile and run [WayBack] Web Service Toolkit – Free Pascal wiki:

Build steps

FPC installation

  1. Run the 32-bit installer
  2. Keep all options except on the second install screen, disable Associate .inc files with FreePascal IDE
  3. Add C:\FPC\3.0.4\bin\i386-win32 to the user path

Building

  1. Recursively unzip wst-0.7u.zip
  2. Open a command prompt in the wst-0.7u directory
  3. Verify there is a ws_helper subdirectory
  4. …
  5. …
  6. …
  7. …

When compiling in Delphi, then you definitely need the FreePascal RTL sources for the PasTree unit; see [WayBack] fcl-passrc – Free Pascal wiki.

Related:

–jeroen

Posted in Conference Topics, Conferences, Delphi, Development, Event, Software Development | 1 Comment »

Keep Your Project Files Clean With Project Magician – The Art of Delphi Programming

Posted by jpluimers on 2020/09/10

Reminder to self to install this to more than just the main dev VM as it combines DProjNormalizer and DProjSplitter, then adds a few more features: [WayBack] Keep Your Project Files Clean With Project Magician – The Art of Delphi Programming

Example of the wizard that shows the additional features

[WayBack] Download

Via [WayBack] Keep Your Project Files Clean With Project Magician – Uwe Raabe – Google+

–jeroen

 

 

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

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