Why I can use Object Initializers in Visual Studio 2008 Windows projects, etc targeted to .NET 2.0 but cannot - in ASP.NET projects targeted to .NET 2.0 ?
I understand that this is C# 3.0 features, but don't - why this possible to use in .NET 2.0 projects.
Probably because the ASP.Net stuff targeting the 2.0 framework assumes it will run in a mode where it may have to compile some code on the fly. Since it is running in 2.0 mode it will get the 2.0 compiler at that stage (thus anything relying on the 3.0 compiler will fail)
When targeting the 2.0 codebase from a 'normal' project the compilation is done then and there so relying on 3.0 compiler functionality is fine.
When you target the .NET 2.0 runtime, you are also targeting the C# 2.0 compiler. That version of the compiler does not understand the 3.0 features.
Here's an existing question that deals with using C# 3.0 features in .NET 2.0 projects. It explains which C# 3.0 features are available, which aren't and how to use them.
In order to help you with any specific difficulty, we'll need specific details.
The best source of information on advanced featured in C# and how they have evolved from C# 1.0 through 3.0 is Jon Skeet's book. He is here on SO quite often and may even offer some additional insight. However, you really should have the book.
A normal ASP.NET Website compiles on the fly, which means it will use the compiler available to that virtual directory on your web server. If it's set to ASP.NET 2.0, it will use the 2.0 compiler (not the 3.0 compiler targeted to .NET 2.0).
I assume when you convert your website to a web application you WILL be able to target 3.0 and still use some of the 3.0 features. I suggest trying that, I would, but I don't have the time at the moment. Let us know if it works ;-)
Related
I use C# with the .NET 1.1 Framework for a Windows application. We have a requirement to upgrade it to .NET 3.5.
Is it possible to upgrade the code directly to 3.5 (or)
Should we follow 1.1 to 2.0 to 3.5?
Which method is more suitable?
Simply convert one of your projects to .NET 3.5 and see what happens. I would even suggest to use 4.5 since that will make your code more future proof. Start from the UI project and work your way down.
Usually your code will work. There are quite some adjustments made in the framework, so if you happen to use some deprecated feature, you need to rewrite your code. Usually the compiler sill suggest you what to do or read.
You would probably want to use new features introduced since .NET 1.1, like generic lists, etc. This will need a further review than just converting your code.
I've inherited an app. The app has to use .NET 2.0. However, I would like to make use of a feature introduce in C# 4.0 (optional arguments). I understand that a framework is separate from a language. However, what I'm not sure of is, can I use this C# feature in the context of .NET 2.0?
The code compiles. I wasn't sure if this was legitimate, or if I just got lucky :).
Thank you for your insights.
Optional arguments/parameters have been supported in CLR since CLR 1.0. This is due to CLR support for VB.net.
This is why your code compiles. Other new 4.0 features may not work the same.
Other post-C# 2.0 features that will compile into a .NET 2.0 application include named arguments, lambda expressions, auto properties, & extension methods.
I maintain a .NET 2.0 library (currently, using Visual Studio 2013).
I have used a code-inspection tool on the code of the library and was surprised when the tool suggested using ?? operator or lambdas instead of some of the code.
I was even more surprised when I applied suggested edits and the library was successfully built after that.
Why the library with Target Framework set to .NET Framework 2.0 can be built with newer features of C# in it's code?
Is it safe to use newer C# features when building for older .NET Framework versions? I mean, the users of the library can have .NET Framework 2.0 only and I want them to be able to use the library even if I use lambdas in it's code.
.NET 2.0 and C# 2.0 are 2 different things. In your case you could perfectly fine have a .NET 2.0 library (which is targeting the CLR 2.0) and use the C# 3.0 compiler which supports for example lambda expressions.
So you should make a difference between your compiler version and the version of the CLR you are targeting. Since you are using VS 2013, you could use newer versions of the compiler.
Is it safe to use newer C# features when building for older .NET Framework versions?
Yes, perfectly safe. The generated assembly is still targeting the CLR 2.0 and will run without any issues with this older version of the CLR.
Basically, new C# language features can be implemented in the compiler without requiring extensions to the underlying .net framework. It isn't always done like that, but it may be.
In the case of lambdas, they were introduced in C# 3.0. So you need a compiler of that level or above. However, the new features introduced in C# 3.0 were all built using the features of .net 2.0. So you can use lambdas under .net 2.0.
In essence, the new functionality here is implemented in the compiler rather than the framework.
As for the null-coalescing operator, ??, it was introduced in C# 2.0 so there's nothing surprising about being able to use it under .net 2.0.
I'm writing a C# class library, which will be used in a project that runs on .NET Framework 1.1. However, I'm using Visual Studio Ultimate 2010, which doesn't provide tooling for version 1.1.
Is there a static check that I can perform inside VS2010 to see that the code is 1.1 compatible?
The csc has the ability to check for syntax compatibility. Use the langversion flag in some post build step to check for program compatibility with ISO-1. I would recommend keeping a separate project for the .NET 1.1 library since the conventions after .NET 2.0 greatly diverge.
There is a problem in backward compatibility in .NET Framework if you build your application in .NET 4.0 than you can not except that this version will work in .NET 1.1 Framework.
A lot of functions are new or obsoleted.
I think a good idea is to build the project in differents target vesions.
Check this information:
http://msdn.microsoft.com/en-us/library/ff602939.aspx
If the C# frontend team on my project makes a standalone program that only does .NET 2.0 API calls, but install on to a computer with .NET 4.0, will it work by default or must they do something to the setup or to the setup-building process (like check off certain checkboxes) to make it work?
See, I'm assuming that if I make .NET 2.0 API calls only, that it should just "work" on .NET 4.0.
Part 2 on this is -- user has .NET 4.0 and .NET 1.1, but not .NET 2.0. I assume .NET 2.0 should work, then, because it has .NET 4.0. Right?
Background -- I'm a Linux/PHP dev and haven't touched C# since 2001. My skills are stale. The client's C# frontend team on my project need some assistance on understanding compatibilities, I guess, and so I've been asked by my client to ask this question.
.NET 2.0 should work if you have .NET 4.0 installed on your computer. I got this from this link: Version Compatibility in the .NET Framework. Keep in mind though, that some objects have changed from 2.0 and 4.0. They might not have all the same properties and methods. It is always a good thing to refer to the MSDN documentation.
Edit new link: Another good reference about the element in the web.config/app.config file of your project: supportedRuntime