We Keep Coding

Can I duplicate an enum into another namespace in c#?

Suppose I'm making a utils library, and among other things I have in it a class that involves key input:
public class KeyInput {
...
public bool IsKeyPressed(Keys key) {
// determine and return whether that key is pressed
}
...
}
The Keys enum is in the standard library, but I'm attempting to make this library so that the user doesn't have to even touch anything outside of it, including the standard library if I can (or at least not to do anything that these utils are intended for). I can use Enum.TryParse() and have the user put in a string according to the what key they want, but it would be much more preferable if I could actually have an enum for it. What I really want is a duplicate of System.Windows.Forms.Keys that has an implicit conversion to it, or alternately some way to make it so that whenever someone uses my namespace, it includes the System.Windows.Forms.Keys enum. Is there any way to do this (or something effectively the same)?

I can't comment yet, so putting this in here.
I understand why you wish to have it in your class/namespace code, so that when someone uses it, they do not have to include any other usings.
Check whether to have an include or using statement inside your namespace, see the differences here: Should 'using' statements be inside or outside the namespace?
Maybe include all functions for the conversion in this class so that if the end user needs to use it, all the functions are handled inside your class.
A couple of options:
So put in all your conversions and functionality that a user could require inside the class, using it almost like a wrapper. Thus defeating the need for the user to include another library.
Have the class output the enum, then if a user uses var output = className.func(); they should not need to include the library.

How to structure classes in a C# program

I have a VSTO (Excel) project written in C#. Three questions:
I have a lot of variables that are populated once and then referenced extensively throughout the project. So I created a public static class which I called "Omni" - since that is both descriptive and short. Is something like this the recommended approach?
I put common functions in a public static class that I named "Utilities". I then used the "this" keyword as the first parameter, making them extension methods. They can then be accessed from anywhere - without using a "Utilities." prefix (although I'm not exactly sure why). Same question: is this the preferred way of doing this?
Finally, I have some common 'subroutines', i.e., public void methods. So parameters are passed in and processed, but nothing is returned. Should such common code just go in its own appropriately named public static class and then get called with the class name as a prefix? If so, is there any convention as to what the name of the class would be?
I realize these are newbie type questions (and I have been searching for a while!). Thanks.

Regarding your points
I have a lot of variables that are populated once and then referenced
extensively throughout the project. So I created a public static class
which I called "Omni" - since that is both descriptive and short. Is
something like this the recommended approach?
Yes, it is common practise to centralize for example string constants that
are often used.
If you have more of those, I would start to structure those to different
classes.
If you want that to be flexible and e.g. have cases where there are
mappings between constants, like Green = 1, I would move to some
enumeration value technology.
More on that idea can be found in this article
If the value does not change between different starts of your application,
check if you can use resources for that, which is often a good choice
for string constants to.
I put common functions in a public static class that I named
"Utilities". I then used the "this" keyword as the first parameter,
making them extension methods. They can then be accessed from
anywhere - without using a "Utilities." prefix (although I'm not
exactly sure why). Same question: is this the preferred way of doing
this?
Extension methods are a handy way of getting things like conversions done.
Just do not everything as an extension, just conversions as a rule of thumb.
Finally, I have some common 'subroutines', i.e., public void methods.
So parameters are passed in and processed, but nothing is returned.
Should such common code just go in its own appropriately named public
static class and then get called with the class name as a prefix? If
so, is there any convention as to what the name of the class would be?
This, in opposite of the others, looks like a design flaw.
Perhaps you can provide more information on what those subroutines do.
In object oriented code, code is distributed near the objects it is working
with. If you depend heavily on code that is in static classes, probably there
is something wrong. Do your static classes have members? Do they share some
knowledge between different calls to your static classes?

C# namespaces: how to follow standards without causing annoying conflicts?

I'm working on a C# library (let's just call it "Foo" for the sake of this question). It has some needs very similar to standard .NET needs: for example, it provides some drawing services, and some conversion services.
For the sake of familiarity and users of the library being able to guess what things are called, I'd like to follow the .NET standard, and name these parts of the library Foo.Drawing and Foo.Convert (and so on). But I'm finding that in actual use, this causes pain. People almost always have "using System;" at the top of each file, and when using this library, they want to have "using Foo;" as well. But now they have two Drawing and two Convert modules, and hilarity ensues.
For example, now instead of just using Drawing.Color for a parameter or variable type, you have to explicitly spell out System.Drawing.Color, or the compiler complains that Foo.Drawing doesn't have a Color type. Similarly, you want to use a standard Convert.ToInt32, you have to say System.Convert.ToInt32, even though you're already using System, because otherwise it finds Foo.Convert and fails to find ToInt32.
I understand why all this is as it is, but I'm still new to the C# community, so I don't know which is the most standard solution:
Leave it this way, and expect users to use fully-qualified names where necessary?
Rename the conflicting modules to something else (maybe Foo.Graphics instead of Foo.Drawing, and Foo.Conversion instead of Foo.Convert)?
Use some prefix on the standard names (Foo.FDrawing and Foo.FConvert)?
Something else?
Any advice from you more experienced C# gurus will be appreciated!

You can use namespace aliasing :
using System;
using FConvert = Foo.Convert;
public class Bar
{
public void Test()
{
var a = Convert.ToInt32("1");
var b = FConvert.ToInt32("1");
}
}

One of the main usage of namespaces is to avoid name clashing.
It means that namespaces allow developers to create types with identical names, as long as the belong to different namespaces.
A library usually have at least a root namespace, and possibly nested namespaces that logically groups the related types.
Name your types as you wish, as long as the names are meaningful and represent what the type really are. A client of your library expects a type named Animal to represent an Animal, not something else. The same applies for naming namespaces.
However, avoid at all cost the names from System, since it will be really annoying for your library clients (as you described) to deal with conflicting names all over the place.
A common way to deal with conflicting namesapces inside a class is to use namespace aliasing:
using FooConvert = Foo.Convert;
using BarConvert = Bar.Convert;

What is Reflection property of a programming language?

Its said that most high-level dynamically types languages are reflexive. Reflection (computer programming) on Wikipedia explains but it doesn't really give a very clear picture of what it means. Can anyone explain it in a simpler way by a relevant example?

To give you a example how to use Reflection in a practical way:
Let's assume you are developing an Application which you'd like to extend using plugins. These plugins are simple Assemblies containing just a class named Person:
namespace MyObjects
{
public class Person
{
public Person() { ... Logic setting pre and postname ... }
private string _prename;
private string _postname;
public string GetName() { ... concat variabes and return ... }
}
}
Well, plugins should extend your application at runtime. That means, that the content and logic should be loaded from another assembly when your application already runs. This means that these resources are not compiled into your Assembly, i.e. MyApplication.exe. Lets assume they are located in a library: MyObjects.Person.dll.
You are now faced with the fact that you'll need to extract this Information and for example access the GetName() function from MyObjects.Person.
// Create an assembly object to load our classes
Assembly testAssembly = Assembly.LoadFile(Application.StartUpPath + #"MyObjects.Person.dll");
Type objType = testAssembly.GetType("MyObjects.Person");
// Create an instace of MyObjects.Person
var instance = Activator.CreateInstance(objType);
// Call the method
string fullname = (string)calcType.InvokeMember("GetName",
BindingFlags.InvokeMethod | BindingFlags.Instance | BindingFlags.Public,
null, instance, null);
As you can see, you could use System.Reflection for dynamic load of Resources on Runtime. This might be a help understanding the ways you can use it.
Have a look on this page to see examples how to access assemblys in more detail. It's basically the same content i wrote.

To better understand reflection, think of an interpreter that evaluates a program. The interpreter is a program that evaluates other programs.
The program can (1) inspect and (2) modify its (a) own state/behavior, or the state/behavior of the interperter running it (b).
There are then four combinations. Here is an example of each kind of action:
1a -- Read the list of fields an object has
2a -- Modification of the value of one field based on the name of the field; reflective invocation of methods.
1b -- Inspect the current stack to know what is the current method that is executed
2b -- Modify the stack or how certain operations in the language are executed (e.g. message send).
Type a is called structural reflection. Type b is called behavioral reflection. Reflection of type a is fairly easy to achieve in a language. Reflection of type b is way more complicated, especially 2b--this is an open research topic. What most people understand by reflection is 1a and 2a.
It is important to understand the concept of reification to understand reflection. When a statement in the program that is interpreted is evaluated, the interpreter needs to represent it. The intepreter has probably objects to model field, methods, etc. of the program to be interpreted. After all, the interpreter is a program as well. With reflection, the interpreted program can obtain references to objects in the interpreter that represent its own structure. This is reification. (The next step would be to understand causal connection)
There are various kinds of reflective features and it's sometimes confusing to understand what's reflective or not, and what it means. Thinking in term of program and interpreter. I hope it will help you understand the wikipedia page (which could be improved).

Reflection is the ability to query the metadata the program that you wrote in run-time, For example : What classes are found inside an assembly, What methods, fields and properties those classes contains, and more.
.net contains even 'attributes', those are classes that you can decorate with them classes, methods, fields and more, And all their purpose is to add customized metadata that you can query in run-time.
Many time details depend on metadata only. At the time of validation we don't care about string or int but we care that it should not be null. So, in that case you need a property or attribute to check without caring about specific class. There reflection comes in picture. And same way if you like to generate methods on a fly, (as available in dynamic object of C# 4.0), than also it is possible using reflection. Basically it help to do behavior driven or aspect oriented programming.
Another popular use is Testing framework. They use reflection to find methods to test and run it in proxy environment.

It is the ability of a programming langauge to adapt it's behaviour based upon runtime information.
In the .Net/C# world this is used frequently.
For example when serializing data to xml an attribute can be added to specify the name of the field in the resultant xml.

This is probably a better question for programmers.stackexchange.com.
But it basically just means that you can look at your code from within your code.
Back in my VB6 days there were some UI objects that had a Text property and others that had a Description (or something other than 'Text' anyway, I forget). It was a pain because I couldn't encapsulate code to deal with both kinds of objects the same way. With reflection I would have at least been able to look and see whether an object had a Text or a Description property.
Or sometimes objects might both have a Text property, but they derive from different base classes and don't have any interface applied to them. Again, it's hard to encapsulate code like this in a statically typed language without the help of reflection, but with reflection even a statically typed language can deal with it.

Help understand syntax of this statement in C#

I'm currently working on DevExpress Report, and I see this kind of syntax everywhere. I wonder what are they? What are they used for? I meant the one within the square bracket []. What do we call it in C#?
[XRDesigner("Rapattoni.ControlLibrary.SFEAmenitiesCtrlTableDesigner," + "Rapattoni.ControlLibrary")] // what is this?
public class SFEAmenitiesCtrl : XRTable

Those are called Attributes.
Attributes can be used to add metadata to your code that can be accessed later via Reflection or, in the case of Aspect Oriented Programming, Attributes can actually modify the execution of code.

The [] syntax above a type or member is called an attribute specification. It allows a developer to apply / associate an attribute with the particular type or member.
It's covered in section 24.2 of the C# language spec
http://www.jaggersoft.com/csharp_standard/24.2.htm

They are called attributes. They are quite useful for providing metadata about the class (data about the data).

They are called Attributes, You can use them to mark classes, methods or properties with some meta-data that you can find by reflection at runtime.
For instance, one common one is Serializable which marks a class as suitable for conversion into an offline form for storage later.

It is called an attribute.
In this case, DevExpress is using custom attributes on their report classes.
If you're interested in why you want to create custom attributes, this article explains it.

Piling on to the previous answers, this is an attribute that takes a string value in its constructor. In this case, the '+' in the middle is a little confusing... it should also work correctly with:
[XRDesigner("Rapattoni.ControlLibrary.SFEAmenitiesCtrlTableDesigner,Rapattoni.ControlLibrary")]