visual basic barcode printing Part I CLR Basics in .NET

Maker QR Code ISO/IEC18004 in .NET Part I CLR Basics

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Answers to these questions and explanations of why each answer is correct or incorrect are located in the Answers section at the end of the book.

public static class Contract { // Precondition methods: [Conditional("CONTRACTS_FULL")] public static void Requires(Boolean condition); public static void EndContractBlock(); // Preconditions: Always public static void Requires<TException>(Boolean condition) where TException : Exception; // Postcondition methods: [Conditional("CONTRACTS_FULL")] public static void Ensures(Boolean condition); public static void EnsuresOnThrow<TException>(Boolean condition) where TException : Exception; // Special Postcondition methods: Always public static T Result<T>(); public static T OldValue<T>(T value); public static T ValueAtReturn<T>(out T value); // Object Invariant methods: [Conditional("CONTRACTS_FULL")] public static void Invariant(Boolean condition); // Quantifier methods: Always public static Boolean Exists<T>(IEnumerable<T> collection, Predicate<T> predicate); public static Boolean Exists(Int32 fromInclusive, Int32 toExclusive, Predicate<Int32> predicate); public static Boolean ForAll<T>(IEnumerable<T> collection, Predicate<T> predicate); public static Boolean ForAll(Int32 fromInclusive, Int32 toExclusive, Predicate<Int32> predicate); // Helper methods: [Conditional("CONTRACTS_FULL")] or [Conditional("DEBUG")] public static void Assert(Boolean condition); public static void Assume(Boolean condition); // Infrastructure event: usually your code will not use this event public static event EventHandler<ContractFailedEventArgs> ContractFailed; }

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Going back to returning a subtree of a given employee, in some cases you might need to limit the number of returned levels. To achieve this, you need to make a minor addition to the original algorithm: Input: @root, @maxlevels (besides root) Algorithm: - set @lvl = 0; insert into table @Subs row for @root

containing the manifest hasn t been tampered with . This check occurs only once, at installation time . In addition, to improve performance, the CLR does not check if a strongly named assembly has been tampered with if the assembly is fully trusted and is being loaded into a fully trusted AppDomain . On the other hand, when a strongly named assembly is loaded from a directory other than the GAC, the CLR verifies the assembly s manifest file to ensure that the file s contents have not been tampered with, causing an additional performance hit every time this file is loaded .

To create a tab on a form, follow these steps: 1. Navigate to Settings area, click Customizations, and then click Customize the System. The default solution opens. 2. Expand the Entities list, select the entity you want to customize, and then click Forms. 3. Open the form you want to edit. 4. On the form ribbon, click the Insert tab. 5. Click the One Column or Two Column button in the Tab section of the ribbon. The new tab appears on your form.

The IAsyncResult APM offers four rendezvous techniques, which complicates the model; however, if you mentally restrict yourself to the callback method technique (as I do), then the model is simplified . The IAsyncResult APM is generally faster and uses fewer resources than the EAP . Some of the classes that support the EAP support cancellation . The IAsyncResult APM doesn t support cancellation at all; however, you can always obtain cancellation behavior by setting a flag and throwing away the result when it does complete . Wrapping the IAsyncResult pattern in a Task and setting the proper ContinueWith callbacks can help you here . The EAP is event-based, so that you can easily use it from within Visual Studio s Windows Forms, WPF, and Silverlight forms designers, and the notifying methods are called in the right UI thread .