Inserts optional parameters when calling a method Boxes value type instances in C#.NET

Generating PDF-417 2d barcode in C#.NET Inserts optional parameters when calling a method Boxes value type instances

Constructs/initializes parameter arrays Binds to members of dynamic variables and expressions Binds to extension methods Binds/invokes overloaded operators Constructs delegate objects Infers types when calling generic methods, declaring a local variable, and using a lambda expression Defines/constructs closure classes for lambda expressions and iterators Defines/constructs/initializes anonymous types and instances of them Rewrites code to support Language Integrated Queries (LINQs; query expressions and expression trees)

And, the CLR itself does all kinds of great things for developers to make our lives even easier . For example, the CLR implicitly:

Invokes virtual methods and interface methods Loads assemblies and JIT-compiles methods which can potentially throw FileLoadException, BadImageFormatException, InvalidProgramException, FieldAccessException, MethodAccessException, MissingFieldException, MissingMethodException, and VerificationException Transitions across AppDomain boundaries when accessing an object of a MarshalByRefObject-derived type which can potentially throw

Serializes and deserializes objects when crossing an AppDomain boundary Causes thread(s) to throw a ThreadAbortException when Thread.Abort or AppDomain.Unload is called Invokes Finalize methods after a garbage collection before objects have their memory reclaimed Creates type objects in the loader heap when using generic types Invokes a type s static constructor potential throwing of TypeInitializationException Throws various exceptions, including OutOfMemoryException, DivideByZeroException, NullReferenceException, RuntimeWrappedException, TargetInvocationException, OverflowException, NotFiniteNumberException, ArrayTypeMismatchException, DataMisalignedException, IndexOutOfRangeException, InvalidCastException, RankException, SecurityException, and more

And, of course, the .NET Framework ships with a massive class library which contains tens of thousands of types each type encapsulating common, reusable functionality . There are types for building Web form applications, Web services, rich GUI applications, working with security, manipulation of images, speech recognition, and the list goes on and on . Any of this code could throw an exception, indicating failure . And, future versions could introduce new exception types derived from existing exception types and now your catch blocks catch exception types that never existed before . All of this stuff object-oriented programming, compiler features, CLR features, and the enormous class library is what makes the .NET Framework such a compelling software development platform .4 My point is that all of this stuff introduces points of failure into your code which you have little control over . As long as everything is working great, all is well: we write code easily, the code is easy to read and maintain . But, when something goes wrong, it is nearly impossible to fully understand what went wrong and why . Here is an example that should really help get my point across:

private static Object OneStatement(Stream stream, Char charToFind) { return (charToFind + ": " + stream.GetType() + String.Empty + (stream.Position + 512M)) .Where(c=>c == charToFind).ToArray(); }

This slightly contrived method contains just one C# statement in it, but this statement does an awful lot of work . In fact, here is the Intermediate Language (IL) the C# compiler produced for this method . (I ve put some lines in boldface italics that are potential points of failure due to implicit operations that are occurring .)

.method private hidebysig static object OneStatement( class [mscorlib]System.IO.Stream stream, char charToFind) cil managed { .maxstack 5 .locals init ( [0] class Program/<>c__DisplayClass1 CS$<>8__locals2, [1] object[] CS$0$0000) L_0000: newobj instance void Program/<>c__DisplayClass1::.ctor() L_0005: stloc.0 L_0006: ldloc.0 L_0007: ldarg.1 L_0008: stfld char Program/<>c__DisplayClass1::charToFind L_000d: ldc.i4.5 L_000e: newarr object L_0013: stloc.1 L_0014: ldloc.1 L_0015: ldc.i4.0 L_0016: ldloc.0 L_0017: ldfld char Program/<>c__DisplayClass1::charToFind

I should also add that Visual Studio s editor, IntelliSense support, code snippet support, templates, extensibility system, debugging system, and various other tools also contribute to making the platform compelling for developers . However, I leave this out of the main discussion because it has no impact on the behavior of the code at runtime .

L_001c: L_0021: L_0022: L_0023: L_0024: L_0029: L_002a: L_002b: L_002c: L_002d: L_0032: L_0033: L_0034: L_0035: L_003a: L_003b: L_003c: L_003d: L_0042: L_0047: L_0048: L_004d: L_0052: L_0057: L_005c: L_005d: L_005e: L_0063: L_0064: L_006a: L_006f:

L_0074: L_0079: }

box char stelem.ref ldloc.1 ldc.i4.1 ldstr ": " stelem.ref ldloc.1 ldc.i4.2 ldarg.0 callvirt instance class [mscorlib]System.Type [mscorlib]System.Object::GetType() stelem.ref ldloc.1 ldc.i4.3 ldsfld string [mscorlib]System.String::Empty stelem.ref ldloc.1 ldc.i4.4 ldc.i4 0x200 newobj instance void [mscorlib]System.Decimal::.ctor(int32) ldarg.0 callvirt instance int64 [mscorlib]System.IO.Stream::get_Position() call valuetype [mscorlib]System.Decimal [mscorlib]System.Decimal::op_Implicit(int64) call valuetype [mscorlib]System.Decimal [mscorlib]System.Decimal::op_Addition (valuetype [mscorlib]System.Decimal, valuetype [mscorlib]System.Decimal) box [mscorlib]System.Decimal stelem.ref ldloc.1 call string [mscorlib]System.String::Concat(object[]) ldloc.0 ldftn instance bool Program/<>c__DisplayClass1::<M>b__0(char) newobj instance void [mscorlib]System.Func`2<char, bool>::.ctor(object, native int) call class [mscorlib]System.Collections.Generic.IEnumerable`1<!!0> [System.Core]System.Linq.Enumerable::Where<char>( class [mscorlib]System.Collections.Generic.IEnumerable`1<!!0>, class [mscorlib]System.Func`2<!!0, bool>) call !!0[] [System.Core]System.Linq.Enumerable::ToArray<char> (class [mscorlib]System.Collections.Generic.IEnumerable`1<!!0>) ret

As you can see, an OutOfMemoryException is possible when constructing the <>c__DisplayClass1 class (a compiler-generated type), the Object[] array, the Func delegate, and boxing the char and Decimal . Memory is also allocated internally when Concat, Where, and ToArray are called . Constructing the Decimal instance could cause its type constructor to be invoked resulting in a TypeInitializationException .5 And then, there are the implicit calls to Decimal s op_Implicit operator and its op_Addition operator methods, which could do anything including throwing an OverflowException .

By the way, System.Char, System.String, System.Type, and System.IO.Stream all define class constructors which could all potentially cause a TypeInitializationException to be thrown at some point in this application .