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 ‘Event’ Category

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Delphi dcc32 error E2506 Method of parameterized type declared in interface section must not use local symbol ‘TExceptionThread`1’

Posted by jpluimers on 2019/07/25

Need to check on this compiler error that you can solve by moving the generic class TExceptionThread<T> from the implementation section of a unit to the interface section.

[dcc32 Error] Test.ExceptionLogging.pas(246): E2506 Method of parameterized type declared in interface section must not use local symbol 'TExceptionThread`1'

My gut feeling is that that this either has to do with RTTI generation, or is a limitation of the compiler.

I need to trim that one done since it does not match any of these:

–jeroen

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

delphi – Why variables are declared as TStrings and created as TStringList? – Stack Overflow

Posted by jpluimers on 2019/07/24

Blast from the past: [WayBack] delphi – Why variables are declared as TStrings and created as TStringList? – Stack Overflow

Q

Why variables are declared as TStrings and created as TStringList?

A

Because that way you could put another TStrings descendant in the SL variable (I’d probably call that Strings, not SL).

In your case, that is moot, since the logic around SL contains the creation of a TStringList and no external assignment or parameter parsing.

But if you ever split the logic away from the assignment, then you could benefit from using any TStrings descendant.

For instance, a TMemoy.Lines, TListBox.Items, TComboBox.Items, etc.
From the outside it looks like they are TStrings, but internally they do not use a TStringList but their own descendant.

A few examples of classes that descend from TStrings:

source\DUnit\Contrib\DUnitWizard\Source\DelphiExperts\Common\XP_OTAEditorUtils.pas:
     TXPEditorStrings = class(TStrings)
source\fmx\FMX.ListBox.pas:
       TListBoxStrings = class(TStrings)
source\fmx\FMX.Memo.pas:
     TMemoLines = class(TStrings)
source\rtl\common\System.Classes.pas:
     TStringList = class(TStrings)
source\vcl\Vcl.ComCtrls.pas:
     TTabStrings = class(TStrings)
     TTreeStrings = class(TStrings)
     TRichEditStrings = class(TStrings)
source\vcl\Vcl.ExtCtrls.pas:
     TPageAccess = class(TStrings)
     THeaderStrings = class(TStrings)
source\vcl\Vcl.Grids.pas:
     TStringGridStrings = class(TStrings)
     TStringSparseList = class(TStrings)
source\vcl\Vcl.Outline.pas:
     TOutlineStrings = class(TStrings)
source\vcl\Vcl.StdCtrls.pas:
     TCustomComboBoxStrings = class(TStrings)
     TMemoStrings = class(TStrings)
     TListBoxStrings = class(TStrings)
source\vcl\Vcl.TabNotBk.pas:
     TTabPageAccess = class(TStrings)

–jeroen

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

Laptop fan profiling, and debugging them – related to Profiling | CommitStrip

Posted by jpluimers on 2019/07/23

A while back, I posted the “profiling” CommitStrip on[WayBack] Profiling – Jeroen Wiert Pluimers – Google+. Boy how did I not know that within a week, I bumped into a “laptop fan profiling” artefact.

A coworker noticed, that when starting a thread based equivalent of [WayBack] TTimer Class (which cannot be used in services as it depends on the VCL), then sometimes the laptop fans would spin up.

What basically happened was that for certain combinations of Enabled and Interval the Execute would loop burning 100% of one CPU core.

With 3 or more – sometimes 2 – of these threads active on a 4+4 core (4 are hyper-threaded), the processor fan would start to spin like madness.

Finding the solution was somewhat easy too:

  • Process Explorer would show the thread IDs burning the most CPU cycles
  • Delphi shows the Thread IDs in the Thread Status pane (if they are named, the ID is at the end of the name in parenthesis)
  • At around Delphi 2010, you can Freeze or Thaw threads. This allows you to debug only a single thread by freezing all others.

Focussing on one thread, allowed a close inspection of the loop, quickly finding the actual cause and repairing it.

TTimer Thread

A similar and better class is at [WayBack] multithreading – TTimerThread – Threaded timer class – Code Review Stack Exchange, based on [WayBack] timer – Using VCL TTimer in Delphi console application – Stack Overflow.

Read the rest of this entry »

Posted in Conference Topics, Conferences, Debugging, Delphi, Development, Event, Fun, Multi-Threading / Concurrency, Profiling-Performance-Measurement, Software Development | Leave a Comment »

CAA Mandated by CA/Browser Forum | Qualys Blog

Posted by jpluimers on 2019/07/22

[WayBack] CAA Mandated by CA/Browser Forum | Qualys Blog

Certification Authority Authorization (CAA), specified in RFC 6844 in 2013, is a proposal to improve the strength of the PKI ecosystem with a new control to restrict which CAs can issue certificates…

Related:

–jeroen

Posted in Conference Topics, Conferences, DNS, Encryption, Event, HTTPS/TLS security, Internet, Power User, Security | Leave a Comment »

delphi – How to hide the inherited TObject constructor while the class has overloaded ones? – Stack Overflow

Posted by jpluimers on 2019/07/18

Interesting, need to try this one day to see how well this works so the base constructor TObject.Create cannot be called.[WayBack] delphi – How to hide the inherited TObject constructor while the class has overloaded ones? – Stack Overflow

–jeroen

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

+Stefan Glienke​ at EKON21: I don’t count sheep, I count references.

Posted by jpluimers on 2019/07/08

+Stefan Glienke​ at EKON21:

I don’t count sheep, I count references.

Response from +Roald van Doorn​:

When you reach -1 you wake up from a nightmare.

Source: [WayBack] Jeroen Wiert Pluimers – G+

Posted in Conferences, EKON, Event, Fun, Quotes, T-Shirt quotes | Leave a Comment »

DelphiTips/RecordProperty at master · tothpaul/DelphiTips · GitHub

Posted by jpluimers on 2019/06/13

Out of the box, Delphi does not support record properties because of two lacking features:

Paul Toth worked around both at [WayBack] DelphiTips/RecordProperty at master · tothpaul/DelphiTips · GitHub

He uses an intermediate helper where he redirects the get/set methods to from a property registration call.

Note that in the past, Pieter Zijlstra did a similar thing, but bumped into a Delphi 2010 problem where the status indicates it is till open: [WayBack] QualityCentral: 77635 – Open – The new RTTI of D2010 causes components with published record properties to fail to stream in.

Source: Yes ! I’ve published a Record property it could be nice to have this feature…

Via: [WayBack] Yes ! I’ve published a Record property it could be nice to have this feature in Delphi, but we need RTTI for record properties to simplify the code (an… – Paul TOTH – Google+

–jeroen

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

Cyclomatic Complexity of switch case statement – Stack Overflow

Posted by jpluimers on 2019/06/12

For my archive: [WayBack/Archive] Cyclomatic Complexity of switch case statement – Stack Overflow.

Ultimate reference: [WayBack/Archive] NIST Special Publication 500-235: Structured Testing: A Testing Methodology Using the Cyclomatic Complexity Metric

Via: [WayBack/Archive] I have a question regarding Cyclometric Complexity… IF versus CASE… – David Hoyle – Google+

–jeroen

Posted in .NET, C#, Conference Topics, Conferences, Delphi, Development, Event, Software Development | Leave a Comment »

The red zone, is why you want immutable constructs

Posted by jpluimers on 2019/05/23

Most code I come across is in the red zone, exactly depicting why you want immutable constructs. Immutable constructs will never end-up in the red zone.

Image: [WayBack] Wayback Machine.

The red zone is just one quadrant on the mutability/shareability diagram and getting outside that red zone quadrant is key.

With processor cores now becoming ubiquitous: you cannot get outside of the “Shard” half, so you have to get outside of the “Mutable” half.

Explaining the why and how, is part of a few presentations that Kevlin Henney gave:

Related YouTube videos are below.

–jeroen

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Posted in Conference Topics, Conferences, Development, Event, Multi-Threading / Concurrency, Software Development | Leave a Comment »

Useful settings for FastMM4 to tracking bottlenecks in multi-threaded memory allocation

Posted by jpluimers on 2019/05/23

Interesting thread that reminded me of the relatively new FastMM feature to track down lock contention and cope with it using release stacks:

[WayBack] I try use FastMM4 to tracking bottleneck in allocating memory. I was inspired by this Primož movie: https://www.youtube.com/watch?v=p-5mJyXvmrc When I… – Jacek Laskowski – Google+

The changes by Primož have added these two new conditional defines to the FastMM4 codebase:

These options are mutually exclusive.

This was the original post it got introduced in [WayBack] The Delphi Geek: Finding Memory Allocation Bottlenecks with FastMM4 and merged into the main repository.

FastMM introduction: [WayBack] The New Memory Manager In BDS 2006 – by Pierre le Riche.

It also taught me about [WayBack] RAMDisk – Software that Accelerates, Protects, Optimizes – Server Memory Products & Services – Dataram.

Primož stores his DCU files there: much faster than SSD, and far less wear on your SSD; see https://youtu.be/p-5mJyXvmrc?t=2675

–jeroen

Read the rest of this entry »

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

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