Story Category: Conference Topics

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DUnit testing code that should raise a specific exception

jpluimers jpluimers A while back, I was writing some code to demonstrate a few inner workings of TInterfacedObject, interface reference counting and mixing object references with interface references. One way to show this is through a test… … Read more 3 years ago in agile, Conference Topics, Conferences, Delphi, Development, Event, Software Development, Unit Testing 0

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If you use an implementation of TNonRefCountInterfacedObject, then document in the descendants how lifetime management is arranged for

jpluimers jpluimers There are a few TNonRefCountInterfacedObject (or maybe better named TNonReferenceCountedInterfacedObject) implementations around (see list of links below). They can be used to expose interfaces, but do not provide interface reference counting. This means you have… … Read more 3 years ago in Conference Topics, Conferences, Delphi, Development, Event, Software Development 0

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Want to use SmartPointers in Delphi? Use the Spring4D one: it is unit tested and optimised

jpluimers jpluimers A while ago, there was a nice discussion on smart pointers at [WayBack] Smart Pointers – Generics vrs non-generic implementastion – RTL and Delphi Object Pascal – Delphi-PRAXiS [en]. Conclusion from that: many people think that… … Read more 3 years ago in Conference Topics, Conferences, Delphi, Development, Event, Software Development, Spring4D 0

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Delphi processing all Windows messages

jpluimers jpluimers Since I had captures messages inside the main message loop, I forgot it is straightforward: create a [WayBack] TApplicationEvents instance, then use the [WayBack] OnMessage event and hook it to a method like procedure TMainForm.ApplicationEventsMessage(var Msg: TMsg; var… … Read more 3 years ago in Conference Topics, Conferences, Delphi, Development, Event, Software Development 0

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How to debug Delphi JSON export stack-overflows: watch the fields and their circular references

jpluimers jpluimers Unlike Delphi RTL XML support which is property based, the JSON support is field based. By default, JSON uses all fields (no matter their protection level, so anything from strict private to published  is taken into… … Read more 3 years ago in Conference Topics, Conferences, Delphi, Development, Event, Software Development 0

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In Delphi, avoid having a TComponent descendant implement interfaces, unless you are prepared to handle your refcounting

jpluimers jpluimers Every now and then I see code, where a class descending from TComponent implements some interfaces, only interface references are used to the instances, and the expected behaviour is that the instances will free themselves when… … Read more 3 years ago in Conference Topics, Conferences, Delphi, Development, Event, Software Development 0

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A bunch of Spring4D dependency injection container related questions

jpluimers jpluimers Since G+ is down, a lot of interesting questions have vanished. Luckily I saved some by [WayBack] Jacek Laskowski – Google+ related to Spring4D and dependency injection: [WayBack] Spring4D IoC and specific singleton… – Jacek Laskowski –… … Read more 3 years ago in Conference Topics, Conferences, Delphi, Development, Event, Software Development 0

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Do not make methods protected unless you want them to be visible as public

jpluimers jpluimers One of the protection levels in Delphi is protected. Originally meant for the class itself, that level is also visible to “friends”: anything in the same unit, for example: unit BusinessLogicUnit; interface type TBusinessLogic =… … Read more 3 years ago in Conference Topics, Conferences, Delphi, Development, Event, Software Development 0

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delphi – What are the list of all possible values for DVCLAL? – Stack Overflow

jpluimers jpluimers From a while ago, from notes even longer ago – around 1994 on DVCLAL the Delphi VCL Access License code which is actually a checking logic for determining the SKU (stock keeping unit) or Delphi… … Read more 3 years ago in Conference Topics, Conferences, Delphi, Development, Event, History, Software Development 0

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Tracking down Delphi “abstract error” occassions.

jpluimers jpluimers A few tips. Set breakpoints in these units: System.pas: procedure _AbstractError; begin if Assigned(AbstractErrorProc) then AbstractErrorProc; RunErrorAt(210, ReturnAddress); end; System.SysUtils.pas: procedure AbstractErrorHandler; begin raise EAbstractError.CreateRes(@SAbstractError); end; add a watch for ClassName that has “Allow side… … Read more 3 years ago in Conference Topics, Conferences, Delphi, Development, Event, Software Development 0

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Be careful changing the DataContext of a TRemotable

jpluimers jpluimers Still not sure why the RTL code is like this: procedure TRemotable.SetDataContext(Value: TDataContext); begin if (RemotableDataContext <> nil) and (RemotableDataContext = Self.DataContext) then begin TDataContext(RemotableDataContext).RemoveObjectToDestroy(Self); end; FDataContext := Value; end; It means that if you… … Read more 3 years ago in Conference Topics, Conferences, Delphi, Development, Event, Software Development 0

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Pointers are dangerous – twm’s blog

jpluimers jpluimers TL;DR Do not keep pointers to objects in memory that can be relocated. SetLength can relocate the memory [WayBack] Pointers are dangerous – twm’s blog Via: [WayBack] Pointers can be really helpful, especially they can improve… … Read more 3 years ago in Conference Topics, Conferences, Delphi, Development, Event, Software Development 0

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Learned about the {$EXTENSION zzz} or {$E zzz} Delphi directive: {$EXTENSION yyy.zzz} fails

jpluimers jpluimers I totally missed that this has been added in Delphi a long time ago (at least in Delphi 2007 or maybe even before): the {$EXTENSION zzz} or {$E zzz} Delphi directive that sets the file extension… … Read more 3 years ago in Conference Topics, Conferences, Delphi, Development, Event, Software Development 0