I'm working on app which uses a lot of external assemblies (newtonsoft.dll, Yahoo Yui compressor.dll, fleck.dll etc). In each c# file I need to add using statement with all those assemblies. Is it possible to create my own assembly (i.e. LIBRARY.dll) containing all the dll's and refer only to this in all c# files?
No. Firstly, using directives refer to namespaces, not assemblies (assembly references are defined at the project level). Secondly: you almost certainly don't actually need all of them in every file. But: you can create a new-file-template with the ones you are likely to need. But frankly it is usually easier to either copy/paste them, or just add them when they are needed. In the IDE, this is as simple as pressing ctrl+.,ret after a type name that doesn't resolve... so MySpecialTypectrl+.,ret should add the missing using directive to resolve MySpecialType.
using does not refer to assembly, but to namespace. So the answer is "no"...
using System; // you are using items in the System namespace
using System.IO; // you are using items in the System.IO namespace
No. Usages of individual types need to be resolved to the namespaces where they are defined in. So, you will still need to include the resolution paths in your usings.
Related
In Visual Studio 2022 we have the classic search function with which we can find a particular string of text in our solution. I'm wondering if there is a way to lookup all the classes inside a file that are defined in a package that is imported via the using directive.
Say for example i'm using package x.Business in my namespace using x.Business; is there a way to then lookup the classes inside this namespace which are coming from this imported package?
What I think you're asking is... "In any class file in my own solution, I want to be able to identify which types used in it (for parameters, variables, etc) are from a particular assembly that is in a using directive."
I don't know of any tool that does this, but the easiest way to identify usages in your file is to comment out the using directive. Any types, methods, etc that exist in that namespace will turn red showing that they can't be found.
(By the way, now is a good time to learn the proper term for those lines at the top of the class files. They're called "using directives", and they're not importing a whole package necessarily, but rather a particular namespace. Not to be confused with "using statements", which are a statement you can write inside of a method that automatically handles disposing of resources.)
I am using resharper to do a big refactoring and i keep going from file to file and adding the same namespace over and over again in the "using" section
is there anyway to add a "using" statement to every single file in a folder, namespace or project? Even though some files wont need the reference, most do, so it will save lots of time.
I'd try a regex in the "Find and Replace" dialog:
Replace
^using System;$
with
using System;\nusing xxx;
This works only for files using the System namespace, but maybe you find another common namespace or structure element. After doing so you can refactor all files in your solution(/folder) with the resharper. That will remove doubled usings.
Update: Did you introduce new namespaces for existing types? There is a refactor function called "move". It will move your type to a new namespace and preserve the references.
Open ReSharper Options / Languages / C# / Namespace Imports
Add "Namespaces that should always be imported"
Run Code Cleanup against solution or project. You may want to create profile (Options / Tools / Code Cleanup) with only Optimize Using Directives module.
VS will add them for you. When you add a symbol in a referenced assembly, but without a using statement for the symbol, you will get a marker against the symbol. Press control-period (or use the mouse) and the first option will add the using statement for you.
Otherwise you could write a VS macro to open each project source file in turn and insert the statement.
I feel it's worth adding an answer to this old question, now that we have "global using directives" in C#10. It renders this requirement moot for newer codebases targeting C#10 and above.
We can now just put one global using in one file, for it to be accessible everywhere in the solution.
global using yournamespace
See the documentation here https://learn.microsoft.com/en-us/dotnet/csharp/whats-new/csharp-10#global-using-directives
When you encounter a file, one-by-one, press CTRL+ALT+SHIFT+F for the automated file cleanup routine. It just takes a second to run, and will do what you're looking for, but not just for System.
not sure if R# has a way to do solution wide file cleanups.
I wasn't able to set my new form as a startup form, it complained about it not existing.
But after some minutes I tried with typing "Namespace.NewForm" and that worked.
In my other project, The startup is set as this:
Application.Run(new MyForm());
Why did I have to specify namespace when changing startup form in this project?
Presumably because you didn't have a using directive for it:
using SomeNamespace;
...
Application.Run(new SomeForm());
There's nothing particularly different about the code used to call Application.Run - it's just normal C# code, following the normal rules of C#.
Use a using directive so you do not have to fully qualify the types within the namespace in question.
using MyNameSpace;
It's also worth pointing out that using directives in C# do not give you access to namespaces nested in the namespace you specify (just in case you are wondering). This means that
using System;
does not give you access to System.IO
It sounds like there's more context here than you're sharing. Regardless of what you're doing, any place where you reference MyForm will need to be able to resolve that reference to a fully-qualified class (including namespace). This means that it will either need to be fully-qualified or it will need its namespace included in the using statements at the top of the file (and be unambiguous).
Does your "working" version already have the using directive and the "non-working" version simply does not? Do your versions attempt to set the startup form in different places?
I suspect that the "working" version has the using directive already in place and that, for whatever reason, it's not in place in the "non-working" version.
(Yet another question from my "Clearly I'm the only idiot out here" series.)
When I need to use a class from the .NET Framework, I dutifully look up the documentation to determine the corresponding namespace and then add a "using" directive to my source code:
using System.Text.RegularExpressions;
Usually I'm good to go at this point, but sometimes Intellisense doesn't recognize the new class and the project won't build. A quick check in the Object Browser confirms that I have the right namespace. Frustration ensues.
Using HttpUtility.UrlEncode() involved adding the appropriate directive:
using System.Web;
But it also required adding a reference to .NET Framework Component for System.Web, i.e. right-click the project in Solution Explorer, select Add Reference and add System.Web from the .NET tab.
How might I discern from the documentation whether a .NET namespace is implemented by a .NET Framework Component that must be referenced? I'd rather not hunt through the available components every time I use a namespace on the off chance that a reference is needed.
(For those who like to stay after class and clean the erasers: Will Organize Usings > Remove and Sort also remove references to componenents that are not used elsewhere in the project? How do you clean up unnecessary references?)
Check out this link for UrlEncode:
Namespace: System.Web
Assembly: System.Web (in System.Web.dll)
The Assembly line tells you which dll to reference.
You'll note that the documentation (e.g. http://msdn.microsoft.com/en-us/library/system.web.httputility.aspx) tells you the name of the assembly/DLL that the class should be found in, along with the class's namespace.
Namespace: System.Web
Assembly: System.Web (in System.Web.dll)
On a side note, I know it can be a little dear, but Resharper makes things like this so much easier. If you're a serious developer, you may want to consider investing in a license. For the eraser-cleaners, Resharper adds a handy little "Find Code Dependent on Module" item to the right-click menu on references in the Solution Explorer. It's not quite an automatic cleanup, but it makes it a lot easier to see whether something's still being used by your project.
The documentation specifies two things for any type:
The namespace of the type (for the using directive)
The assembly containing the type (this is what you add a reference to)
To take an example where the two are different, look at the documentation for Enumerable:
Namespace: System.Linq
Assembly: System.Core (in System.Core.dll)
If you look at the MSDN docs, e.g.
http://msdn.microsoft.com/en-us/library/system.web.httputility.aspx
It tells you the namespace and the assembly that is required.
First, a correction to your terminology: What you are referencing is called an "assembly". An assembly contains classes that belong to a namespace. A namespace can span across multiple assemblies.
Most assemblies are named the same as the main namespace that is contained in them. For example, System.Web exists in System.Web.dll. The documentation also usually tells you which assembly needs to be referenced.
I think that you are running into a difference between c# and C here. To compare: In C, all you need to do to include a new library is to include it in the header.
It .net, you need to be aware of 2 things:
A namespace can span more than one assembly/dll (that means that you might not get a compiler error on the using clause, because some of the dlls that support that namespace are referenced -- just not the one that you need)
To "see" the contents of a given assembly, you have to add a reference to it. The using clause alone just gives you some short-cut syntax so that you can write HttpUtility.Encode(), instead of System.Web.HttpUtility.UrlEncode(), you have to add the reference in order for the compiler to "know" about the class.
To avoid your problem:
In the MSDN documents, pay attention to the assembly that the class is in, and make sure that you have a reference to the assembly.
If you browse to the MSDN for the class you're trying to use. It typically tells you the assembly that the class is in. For example the Regex class is in Assembly System (in System.dll) or the HttpUtility class is in Assembly System.Web (in System.Web.dll).
I believe tools such as ReSharper help with this, as well, and automatically references the assemblies you need.
I'm pretty sure you have to manually remove the unused references in C# projects. In VB.NET projects there's a button to list the unused references when you're in the project properties page. I don't see this in C# projects, though.
If you have
using XXXX.YYYY;
at the top of a C# file, do you need to include that assembly in the References part of the project?
What is the difference?
The references are needed to be added, so that they may be physically located by the compiler at compile time.
For more details watch it at http://en.csharp-online.net/CSharp_FAQ:_Why_add_a_using_statement_and_a_reference
Hope this helps.
Thanks,
Madhup
The "using" keyword is a way of avoiding having to type out the whole namespace for a class every time if it lives outside the current namespace.
For example, if I have namespace foo and I want to reference MyClass in namespace bar I can either write:
bar.MyClass = new bar.MyClass();
or
using bar;
...
MyClass = new MyClass();
The references part of the project tells the compiler which libraries outside the current project to search for the class bar.MyClass
So in short you don't need to put the using statement (but it generally makes the code easier to read and less for you to type) but you do need the referenced assembly.
You don't write using XXXX.dll at the top of a CS File.
I believe you're referring to using NamespaceX; which is a way of categorizing your classes into distinct logical partitions. So I'd group all of my Data Access classes into a namespace called MyProject.DataAccess. An assembly can contain classes belonging to multiple namespaces.
In which case, you need to reference the assembly X if you want to use some types/classes defined in assembly X with that namespace.
The using statement states you want to import a namespace into the file, giving you shorthand access. For example you can write File.Delete(file) instead of System.Io.File.Delete(file) if you imported the System.Io namespace. The namespace you are including should be available in one of your references assemblies. As fasr as I know, you can't reference DLL's directly like that from your code.