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vb.net 128 barcode generator PARAMETERIZED FUNCTIONS AND TYPES in C#.NET
CHAPTER 11 PARAMETERIZED FUNCTIONS AND TYPES Create PDF-417 2d Barcode In Visual C# Using Barcode generator for .NET framework Control to generate, create PDF 417 image in VS .NET applications. www.OnBarcode.comScanning PDF 417 In Visual C#.NET Using Barcode recognizer for VS .NET Control to read, scan read, scan image in .NET applications. www.OnBarcode.comproperty ListNode<T>^ Current { ListNode<T>^ get() { if (theList->changed) throw gcnew InvalidOperationException(); return current; } } virtual bool MoveNext() { if (theList->changed) throw gcnew InvalidOperationException(); beginning = false; if (current != nullptr) { current = current->next; } else current = theList->First; if (current != nullptr) return true; else return false; } virtual void Reset() { theList->changed = false; current = theList->First; } ~ListEnumerator() {} }; // end of ListEnumerator }; // end of MyList int main() { MyList<int>^ int_list = gcnew MyList<int>(); int_list->Add(10); int_list->Add(100); int_list->Add(1000); int_list->Add(100000); Making QR In C# Using Barcode drawer for .NET framework Control to generate, create QR image in Visual Studio .NET applications. www.OnBarcode.comPDF417 Drawer In C# Using Barcode generation for .NET Control to generate, create PDF-417 2d barcode image in Visual Studio .NET applications. www.OnBarcode.comCHAPTER 11 PARAMETERIZED FUNCTIONS AND TYPES
1D Barcode Generator In Visual C#.NET Using Barcode maker for VS .NET Control to generate, create 1D Barcode image in .NET applications. www.OnBarcode.comGS1 - 12 Printer In C# Using Barcode generator for .NET framework Control to generate, create GS1 - 12 image in .NET framework applications. www.OnBarcode.comint_list->Add(500); int_list->Remove(10); int_list->Remove(1000); int_list->Remove(500); int_list->Add(50); // Iterate through the list using the for each statement, // displaying each member of the list at the console. for each (ListNode<int>^ node in int_list) { Console::WriteLine(node->item); // int_list->Remove(50); // danger: modifying the collection } } The output of Listing 11-8 is as follows: 100 100000 50 There are a few points to notice about Listing 11-8. Recall the IEnumerable implementation on a deck of cards in 9 (Listing 9-15). In that example, we chose to implement the nongeneric IEnumerable. Implementing the generic IEnumerable<T> adds an additional layer of complexity because IEnumerable<T> also inherits from IEnumerable. That means MyList must implement two different versions of GetEnumerator: one for the generic IEnumerable and one for the nongeneric interface. This is done via explicit interface implementation. In fact, just as in Listing 9-15, we make the interface implementation methods private and define a public method that for each actually uses and that the private interface implementation functions call. This helps improve performance since the enumeration does not require a virtual function call. Note also that we had to add a destructor to the ListEnumerator class. Without the destructor, the compiler complains that we did not implement IDisposable::Dispose. This is because IEnumerator<T> also inherits from IDisposable (the nongeneric IEnumerator does not). A C++/CLI destructor on a managed type is emitted as the Dispose method, as discussed in 6. Finally, we have added a Boolean field in MyList that detects whether MyList is changed during the enumeration. As you may recall, in Listing 9-15, we made a copy of the card deck and used it in the enumerator class. With this version, you avoid the copy, which could be expensive for a large list, and instead generate an exception when the list is modified. To demonstrate the exception, try uncommenting the line calling the Remove method during the iteration. If we permitted the item to be successfully removed during the iteration, the collection would be considered corrupted, and the enumeration would produce undefined results. The behavior of for each would not be as expected and would be very confusing for consumers of the type. Unless you create a working copy of the collection, you should always implement some code that checks that the type has not been modified. Code 3 Of 9 Printer In Visual C# Using Barcode generator for .NET Control to generate, create Code 3 of 9 image in .NET framework applications. www.OnBarcode.comPlanet Creation In C# Using Barcode maker for .NET Control to generate, create USPS PLANET Barcode image in .NET applications. www.OnBarcode.comCHAPTER 11 PARAMETERIZED FUNCTIONS AND TYPES
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Paint Data Matrix 2d Barcode In Objective-C Using Barcode creator for iPhone Control to generate, create DataMatrix image in iPhone applications. www.OnBarcode.comMatrix 2D Barcode Printer In Visual Basic .NET Using Barcode encoder for Visual Studio .NET Control to generate, create 2D Barcode image in VS .NET applications. www.OnBarcode.comThe restriction noted previously on the use of methods, properties, and other constructs on a type parameter would severely limit the usefulness of generic types, were it not for the ability to get around the restriction by using constraints. Constraints are specific requirements put on a type parameter that limit, or constrain, the types that may be used as type arguments. Essentially, the constraints limit the possible type arguments to a subset of all possible types. By imposing constraints, you may write generic code that uses the methods, properties, and other constructs supported by the constrained subset of types. There are several types of constraints: interface constraints, class constraints, the gcnew constraint, and constraints that limit the type arguments to either reference types or value types. Barcode Scanner In VS .NET Using Barcode decoder for .NET framework Control to read, scan read, scan image in .NET applications. www.OnBarcode.comGTIN - 128 Encoder In Java Using Barcode generator for Java Control to generate, create UCC-128 image in Java applications. www.OnBarcode.comInterface Constraints
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