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 10 Seattle’ Category

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Interface methods are not assignment compatible with method references or methods of object.

Posted by jpluimers on 2019/04/02

Boy I wish that QC was still up and QualityPortal was publicly indexable as that would have saved me quite a bit of time tracking this down. Luckily I got help from Stefan Glienke (who maintains the awesome Spring4D library based on modern Delphi compiler support) when I mentioned

How good are you with reference to function?
I’ve an odd compiler thing throwing errors when using interfaces but not with classes.

So, for posterity:

Unlike C#, in Delphi interface methods are not compatible with method references or methods of object.

This has many manifestations, which means you can get a variety of compiler errors. I’ve listed the ones I could find below, but presume there are more and if I find more will update this post.

These are the errors you can get:

  • E2010 Incompatible types: ‘T’ and ‘Procedure’
  • E2035 Not enough actual parameters
  • E2250 There is no overloaded version of ‘FirstOrDefault’ that can be called with these arguments

These are the (now defunct, but used to be publicly accessible) QC and QualityPortal (needs sign on) entries (thanks Stefan Glienke and Blaise Thorn for reporting these):

The really frustrating part is that the RSP is marked as “new feature” whereas clearly it isn’t, so it probably never will be fixed.

A workaround for now is to wrap the interface method references with:

  • either anonymous methods (when you have just a few classes to cover, but maybe more than a few methods on the interface)
  • or instance methods on a class (when there are many classes to cover and preferably few methods on the interface)

Examples are in the code below that also shows this works fine and dandy in C#.

–jeroen

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Posted in Delphi, Delphi 10 Seattle, Delphi 10.1 Berlin (BigBen), Delphi 10.2 Tokyo (Godzilla), Delphi XE3, Delphi XE4, Delphi XE5, Delphi XE6, Delphi XE7, Delphi XE8, Development, Software Development, Spring4D | Leave a Comment »

There can be only MS Office sample automation server wrapper components in RAD Studio

Posted by jpluimers on 2019/02/27

There are six variations; only one can be active at a time:

  • Delphi Office 2000 Servers Package
  • Delphi Office XP Servers Package
  • Delphi Office 2010 Servers Package
  • C++Builder Office 2000 Servers Package
  • C++Builder Office XP Servers Package
  • C++Builder Office 2010 Servers Package

via: I cannot get MS Office sample automation server wrapper components. Neither of… [WayBack]

More in depth article explaining all the nitty gritty details: There Can Only Be One! Handling Different Versions of Design Packages inside the IDE | The Art of Delphi Programming [WayBack]

–jeroen

Posted in Delphi, Delphi 10 Seattle, Delphi 10.1 Berlin (BigBen), Delphi 2005, Delphi 2006, 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 | Leave a Comment »

“Don’t access VCL from a background thread” – how to demo that?

Posted by jpluimers on 2018/07/11

When accessing the VCL from multiple threads at the same time: adopted from ...\DEMOS\THREADS\THRDDEMO.DPR

When accessing the VCL from multiple threads at the same time: adopted from …\DEMOS\THREADS\THRDDEMO.DPR

Great question a while ago:

[WayBack] “Don’t access VCL from a background thread” – how to demo that? – Primož Gabrijelčič – Google+

For me, the ultimate way why not to access the VCL from a background thread is the precursor of the official threads demo that ships from Delphi 2 to Delphi XE6 in ...DEMOS\THREADS\THRDDEMO.DPR. where you’d think the thread isolation would be in ...DEMOS\THREADS\ThSort.pas but actually is in ...DEMOS\THREADS\SortThds.pas.

The first public showing of that demo did not include main thread protection. It originates from a session at the the 1995 Borland Developers Conference where Ray Konopka showed the below code from Bob Ainsbury.

That session reminded why this joke [WayBack] Via the EKON20 sessions… – Jeroen Wiert Pluimers – Google+ was so funny:  “When Ray Konopka enters the room you have a Raize condition.“.

The question above also made me find back this reference to BorCon95 in San Diego:

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Posted in Delphi, Delphi 10 Seattle, Delphi 10.1 Berlin (BigBen), Delphi 10.2 Tokyo (Godzilla), 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 x64, Delphi XE, Delphi XE2, Delphi XE3, Delphi XE4, Delphi XE5, Delphi XE6, Delphi XE7, Delphi XE8, Development, Software Development | 2 Comments »

I totally forgot that Delphi has had a function to get the current executing thread – Stack Overflow

Posted by jpluimers on 2018/07/05

While updating some old code fiddling with the[WayBack] GetThreadId function, I wanted to have some TThread wrapper around it. I had totally forgotten there has been already a means for this since Delphi 2009 (which initially had a bug, but that was worked around at first and fixed later): [WayBack] CurrentThread.

The latest version of Delphi, Delphi 2009, has a CurrentThread class property on the TThread class.

This will return the proper Delphi thread object if it’s a native thread. If the thread is an “alien” thread, i.e. created using some other mechanism or on a callback from a third party thread, then it will create a wrapper thread around the thread handle.

20081001 at 5:00 – [WayBack] Barry Kelly

Sources

–jeroen

Posted in Delphi, Delphi 10 Seattle, Delphi 10.1 Berlin (BigBen), Delphi 10.2 Tokyo (Godzilla), Delphi 2010, Delphi XE, Delphi XE2, Delphi XE3, Delphi XE4, Delphi XE5, Delphi XE6, Delphi XE7, Delphi XE8, Development, QC, Software Development | Leave a Comment »

Delphi, IBX and the Turkish I problem

Posted by jpluimers on 2018/06/13

Last year, it took a while to reproduce and it is likely not fixed anytime soon: if you use Delphi and IBX (InterBase Express) to connect to either InterBase or FireBird database, then in the Turkish locale do not use lowercase SQL in your Delphi code as it will break on the

I’ve decided to put this in a separate post than the one I discovered the issue in as that one focused on the Unicode and language background of the various i/I/ characters and this post on the Delphi part.

So for the non-Delphi part, read Source: Field “id” not found and the The Turkish-İ/I/i/ı and case conversion – Update on the dasBlog Turkish-I bug and a reminder to me on Globalization – Scott Hanselman.

More recently, I learned that the same problem also happens in the Azeri language or Azerbaijani language – Wikipedia via [WayBack] SQL Instance Collation – Language Neutral Required:

…

uppercase / lowercase mappings (though this only impacts 2 characters — dotted and dotless “i”/”I” — and for only 2 cultures — Azeri and Turkish)

…

In general, this problem is called [WayBack] Case Folding and many environments do not have good and ready to use solutions for this.

Basically when working with case-insensitive language identifiers, you should always use culture invariant text comparison operations. In most languages, people use either lowercase or uppercase converted operations which for Delphi >= come down to using :

The reason is simple:

  • without any parameter, ToLower and ToUpper will use [Archive.is] SysLocale.DefaultLCID.
  • without any parameter, LowerCase and UpperCase will implicitly behave as if called with TLocaleOptions.loInvariantLocale, but lots of people forget they do.

The functions ToLowerInvariant and  ToUpperInvariant  were added in Delphi XE3, but ToLower(LocaleID) and ToUpper(LocaleID) in Delphi XE4.

Instead of doing uppercase and lowercase comparisons you could also use the [Archive.is] System.SysUtils.CompareText function.

IBX however uses case conversion, and by now you will probably guessed it: IBX got it all wrong. One reproduction is at https://gist.github.com/jpluimers/643b382944ff991d07ec96abbf85548c and a thread with background is at [WayBack] What’s the Delphi equivalent of doing UpperCase with an InvariantCulture in Unicode Delphi versions? (XE and up) – Jeroen Wiert Pluimers – Google+

IBX isn’t alone: just search for other uppercase issues like Turkish i to see tons of other issues.

For IBX, I did the replacements in the diff below to fix it in Delphi XE8. I only replaced where identifiers were compared, not were actual database content was compared.

Unluckily, in the past IBX sources were hosted on CodeCentral at http://cc.embarcadero.com/Author/102 but no new bundles have been released since 2012.

Of all the locations I think IBX should not have used any case conversion here:

IBX.IBDatabaseINI.pas – function LocalServerPath(sFile: string): string

This function uses LowerCase() but I think an NTFS specific comparison should have been used, but I’ve not investigated into a solution for that yet.

–jeroen

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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 | Leave a Comment »

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