Tag: oop

DeHL 2.2 Released

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In this release I have changed the name of the library from DelphiHelperLib to DeHL to be shorter. The most important changes in this release are: Renamed the library to DeHL in hopes to remove the length of…

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How To: Creating a custom Variant type

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In this post I will detail on how to create a custom Variant for your data type. First of all, the help should be pretty useful in this case, but it if doesn’t help much, there is always…

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Delphi Generics: constructor restriction

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As promised in the previous post “Delphi: Default parameterless constructor” I will now try to create a new generic class that accepts a type parameter that has a “constructor” restriction (must have a default public parameterless constructor). Let’s…

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Delphi: Default parameterless constructor

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A weird consequence of Delphi’s OOP behavior is how constructors are handled, and in particular how the default parameterless constructor is handled. Consider the following example: [Delphi] type TMyClass = class end; var Obj: TMyClass; begin Obj :=…

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Abstract methods (or “why not”)

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I always considered the implementation of abstract methods in Delphi to be a hack, mostly because there is no way (or is there?) to treat this: “[DCC Warning] W1020 Constructing instance of a class containing abstract method.” warning…

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Overridden method should match case of ancestor

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I’ve been following CodeRage III these days and presenter mentioned that in Delphi 7 (and above), when overriding virtual methods, the same case should be used for both functions. Consider this example: In this case indeed the compiler…

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