c#-6.0 | 易学教程

Which “C# Experimental language feature” is this?

阅读更多关于 Which “C# Experimental language feature” is this?

问题 In the example below, Resharper shows "C# Experimental language feature" tooltip on the first curly bracket. I've checked the new features of C# 6.0 but didn't come across a similar one. What is the referred experimental feature? class Class1 { { // <= C# Experimental language feature } } Note: It is an error for .Net Framework 4.5 compiler. "Invalid token '{' in class, struct, or interface member declaration" 回答1: This was for Primary Constructors, a feature which has now been cut from C#6.

Overloaded string methods with string interpolation

阅读更多关于 Overloaded string methods with string interpolation

Why does string interpolation prefer overload of method with string instead of IFormattable ? Imagine following: static class Log { static void Debug(string message); static void Debug(IFormattable message); static bool IsDebugEnabled { get; } } I have objects with very expensive ToString() . Previously, I did following: if (Log.IsDebugEnabled) Log.Debug(string.Format("Message {0}", expensiveObject)); Now, I wanted to have the IsDebugEnabled logic inside Debug(IFormattable) , and call ToString() on objects in message only when necessary. Log.Debug($"Message {expensiveObject}"); This, however,

TeamCity Build using C#6

阅读更多关于 TeamCity Build using C#6

问题 We use TeamCity (9.0.1) as our build server, but having recently upgraded our ASP.NET MVC solution to use VS2015 and C#6 syntax, I now get the following error message on our build server: Can not start build runner and more specifically: C:\TeamCity\buildAgent\work\86ee61c6c333dc3d\MyApplication\MyApplication.csproj.metaproj : error MSB4025: The project file could not be loaded. Could not find file 'C:\TeamCity\buildAgent\work\86ee61c6c333dc3d\MyApplication\MyApplication.csproj.metaproj'. I

nameof with Generics

阅读更多关于 nameof with Generics

问题 I was experimenting with nameof with generics. I didn't get the result I was expecting. I'm not sure if this is part of the spec or not. class MainClass { public static void Main (string[] args) { Console.WriteLine ($"Hello { nameof(FooBar<string>)! }"); } } class FooBar<T> { } The output I get is Hello FooBar! I would expect some details about the type parameters. I tried it with a method and that fails with a compiler error: class MainClass { public static void Main (string[] args) {

Interpolate string c# 6.0 and Stylecop

阅读更多关于 Interpolate string c# 6.0 and Stylecop

问题 I am using Stylecop version : 4.7.49.0 Has anyone used the latest interpolate string functionality in c# 6.0 example var totalUnits = GetUnitsGetTotalIssuedShares(myId); var testString = $"Test Units :{totalUnits}, have been shipped."; When I build i get the stylecop error SA0102 - because stylecop cant parse the file. It doesn't seem like there is a new version of stylecop that can handle 6.0 yet? error :SA0102: A syntax error has been discovered in file Is there anyway around this error?

using statement with static class is not working in visual studio 2015 CTP

阅读更多关于 using statement with static class is not working in visual studio 2015 CTP

I have written a following code for one of my C# 6.0 Sample application. It was working fine earlier with Visual Studio 2015 Preview. But now when I have downloaded the newest version of Visual Studio 2015 which launched before some time.( http://blogs.msdn.com/b/bharry/archive/2015/01/16/visual-studio-2015-ctp-5-is-available.aspx ) it stopped working. Following is a code for that. using System.Console; namespace StaticClassUsing { class Program { static void Main(string[] args) { WriteLine("With using statement"); } } } Now when you run this application in Latest Version of Visual Studio 2015

Null-conditional operator evaluates to bool not to bool? as expected

阅读更多关于 Null-conditional operator evaluates to bool not to bool? as expected

问题 I've just upgraded from VS 2010 to 2015. I like the new null-conditional operator which is also known as null-propagation. This enables to simplify your code, for example: string firstCustomerName = customers?[0].Name; // null if customers or the first customer is null another one: int? count = customers?[0]?.Orders?.Count(); // null if customers, the first customer, or Orders is null which returns a Nullable<int> even if Enumerable.Count returns an int to differentiate between a valid count

Omitted setter vs private setter?

阅读更多关于 Omitted setter vs private setter?

What is the difference between a property with a omitted setter and a property with a private setter? public string Foo { get; private set; } vs public string Foo { get; } In C# 6, get; only properties are only settable from the constructor. From everywhere else, it is read-only. A property with a private set; can be set from everywhere inside that class. Thomas Ayoub From outside the class, it won't change anything if you use this syntax: public string Foo { get; } But you won't be able to update Foo within the class, except in the constructor, to do so, you'll need the private setter: public

Null propagation operator and dynamic variable

阅读更多关于 Null propagation operator and dynamic variable

I have been looking at the null-propagation operator in C#6 and tried to make it work with the variables of dynamic type but without success. Consider the code below, it compiles but CLR throws AccessViolationException at runtime when the null-propagation is applied to dynamic object. class SomeType { public object SomeProperty { get; set; } static void Main() { var obj = new SomeType() { SomeProperty = "ABCD" }; var p1 = ((dynamic)obj).SomeProperty; //OK, p1 is set to "ABCD" var p2 = ((dynamic)obj)?.SomeProperty; //AccessViolationException Console.ReadLine(); } } At first I thought that this

Trying to understand ?. (null-conditional) operator in C#

阅读更多关于 Trying to understand ?. (null-conditional) operator in C#

I have this very simple example: class Program { class A { public bool B; } static void Main() { System.Collections.ArrayList list = null; if (list?.Count > 0) { System.Console.WriteLine("Contains elements"); } A a = null; if (a?.B) { System.Console.WriteLine("Is initialized"); } } } The line if (list?.Count > 0) compiles perfectly which means that if list is null , the expression Count > 0 becomes false by default. However, the line if (a?.B) throws a compiler error saying I can't implicitly convert bool? to bool . Why is one different from the other? Heinzi list?.Count > 0 : Here you compare