Detaylar, Kurgu ve C# ReadOnlyCollectionBase Temel Özellikleri

Detaylar, Kurgu ve C# ReadOnlyCollectionBase Temel Özellikleri

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Average(IEnumerable, Func) Computes the average of a sequence of Decimal values that are obtained by invoking a transform function on each element of the input sequence.

Sum(IEnumerable, Func) Computes the sum of the sequence of nullable Int64 values that are obtained by invoking a transform function on each element of the input sequence.

I had a client recently who wanted me to create a class that exposed a read-only collection through one of the class properties. While my client was willing to let other programs loop through that collection and retrieve items from the collection by position, he didn't want to let those programs add or remove items from the collection. In the Microsoft .Kupkuru Framework 4.5 you emanet use the read-only collections that Eric Vogel covered in an earlier C# Corner column, "The New Read-Only Collections in .NET 4.5," to define that property. My client, however, was working with the .Kupkuru Framework 4 and didn't intend to upgrade. Fortunately, in earlier versions of .Safi you kişi also create a read-only class from an existing List just by calling your List's AsReadOnly method. However, if you need something special (a List that users sevimli add items to but derece remove items from), inheriting from the ReadOnlyCollectionBase class makes that very easy to do.

This hides Add and Remove methods, but does derece protect at all. Because I yaşama always cast to ICollection and call prohibited method.

Now when you use IntelliSense to inspect IReadOnlyList, you’ll no longer see Add among the supported methods. Figure 2 below displays the members of the IReadOnlyList instance.

Your implementation depends on your needs: - If you don't care about the caller (Class B) from seeing any further changes to the collection then you sevimli just clone the collection, hand it out, and stop caring. - If you definitely need the caller (Class B) to see changes that are made to the collection, and you want this to be thread-safe, then you have more of a sorun on your hands.

1. The reason C# ReadOnlyCollectionBase Kullanımı for derece choosing ReadOnlyCollectionBase is simple - it isn't generic, while the aim of ReadOnlyCollection is to be generic. Thus it needs a much different inheritance tree.

Important Some information relates to prerelease product that may be substantially modified before it’s released. Microsoft makes no warranties, C# ReadOnlyCollectionBase Nerelerde Kullanılıyor express or C# ReadOnlyCollectionBase Temel Özellikleri implied, with respect to the information provided here.

Note that the IReadOnlyList interface works similarly to List and in fact birey be used in place of List when you want the elements of the list to C# ReadOnlyCollectionBase Nedir be read-only. We will illustrate this with an example in the next section.

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However, the syntax is awkward. Adding an extension method birey simplify that syntax tremendously. Extension methods have at least three convenient features: The first is that they attach themselves to whatever classes you specify, automatically appearing in the IntelliSense dropdown lists for those objects; second, they're automatically passed whatever object they're called from birli their first parameter; third, when an extension method is used with a generic class (for instance, List), the method automatically figures out the data type of the generic parameter.

If the collection is small then a safe and easy way to get around this sıkıntı is to return a copy instead.

End Sub And that's all you need to write. The class that's using your new read-only collection would be identical to the class that used my custom PhvReadOnlyList. In fact, if that's all you want, then you don't even need to create your own version of the ReadOnlyCollectionBase class -- the .

Key values are compared by using a specified comparer, and the elements of C# ReadOnlyCollectionBase Kullanımı each group are projected by using a specified function.