74 lines
2.0 KiB
Plaintext
74 lines
2.0 KiB
Plaintext
= Interface =
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An interface is a paradigm where an abstract class defines some set of abstract
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functions that a class inheriting it can define. This is a core concept in C#.
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In C# an interface can be declared with the `interface` keyword in its
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declaration. However, there are several built in interfaces that are very
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useful.
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== Built in C# interfaces ==
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=== System.IComparable ===
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Something that wants to be IComparable must impliment
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`public int CompareTo(object obj)`. This must return,
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* Less than zero if the current instance preceds the object specified in sort
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order
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* Zero if the current instance is in the same position in the sort order as the
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given object
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* Greater than zero if the current instance follows the object given
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All numeric types already have this, as do String Char and DateTime
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=== System.IDisposable ===
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Something that is IDisposable can be freed, it is very useful when working with
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unmanaged resources, like database connections or filestreams. To impliment
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this, a class must impliment `public void Dispose()`. This Dispose function
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will be called if the object is used in a `using()` block statement for
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example.
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=== System.IEnumerable ===
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Something that is IEnumerable can be used with an enumerator object. This
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allows some object to work with LINQ queries. IEnumerable also requires
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`IEnumerator<T>` to be defined. `IEnumerator<T>` also needs
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[[#System.IDisposable]] to be implimented.
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{{{
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public class FooEnumerable : IEnumerable<string>
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{
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private string _data;
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//must impliment
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public IEnumerator<string> GetEnumerator()
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{
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return new FooEnumerator(_data);
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}
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//must impliment
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private IEnumerator GetEnumerator1()
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{
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return this.GetEnumerator();
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}
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//now override the IEnumerator one
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IEnumerator IEnumerable.GetEnumerator()
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{
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return GetEnumerator1();
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}
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}
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public class FooEnumerator : IEnumerator<string>
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{
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//required
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public string Current
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{
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get
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{
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return "some val";
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}
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}
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}
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}}}
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