You know how you can have a property that automatically generates a backing field? Like if I go:
public String SomeProperty {get; set;}
I know that if I want to add code to that property I have to create the backing field as so:
public string someProperty = string.Empty;
public string SomeProperty
{
get { return someProperty; }
set
{
someProperty = value;
DoSomething();
}
}
Basically, what I want to know is... is there any way to do this but without having to create the backing field? For example I could use it to trigger some kind of event that occurs when a property is set. I'm looking for something like this:
public string SomeProperty
{
get;
set { this.OnSomeEvent; }
}
But I know that'll cause a compile error because get needs do declare a body if set does.
I've researched and I cant find anything, but I thought I'd check to see if anyone knew.
I guess what I'm really after is some way to trigger an event when a property is changed but without having to add all that extra clutter. Any suggestions?
Simple answer is no, you can't have it both ways. From .NET Docs:
In C# 3.0 and later, auto-implemented properties make property-declaration more concise when no additional logic is required in the property accessors.
There are not any solutions for this built into the framework, and you cannot modify existing types via reflection (in order to add the logic at runtime). The only way to accomplish this seems to be at compile time.
There is a product http://www.postsharp.net/ that can accomplish this (intercept property/method calls), and there does appear to be a free edition.
The field keyword might be added to C#, see https://github.com/dotnet/csharplang/issues/140, which removes "when no additional logic" requirement for auto properties.
It didn't make it into C# 10 nor 11, but latest comment from compiler team says C# version 12 might have it. They release yearly, so that would be Nov 2023.
I have this class:
public class MyProps
{
public MyProps()
{
}
protected string myVar;
public string MyProperty
{
get { return myVar; }
set { myVar = value; }
}
protected int myOtherVar;
public int MyOtherProperty
{
get { return myOtherVar; }
set { myOtherVar = value; }
}
}
That I want to add to my Form, so when I inherit from it I will be able to fill the properties in the MyPropsX property.
I have this code in my form:
protected MyProps propsX = new MyProps();
[TypeConverter(typeof(ExpandableObjectConverter))]
public MyProps MyPropsX
{
get
{
return propsX;
}
set
{
propsX = value;
}
}
Now, the properties MyProperty and MyOtherProperty are nicely shown in the Properties Window, and I can set their values directly there.
But when I close my form and I open it again, all my changes are lost, the properties being reset to show zero and an empty string.
What am I missing?
Should I inherit my MyProps class from certain special class or interfase?
Or some special attribute?
This is a little bit much for a comment and maybe your solution, so i'm answering to your comment with an answer instead with another comment:
With does not happen when I put properties directly on a form you mean, you are using the designer to set some property of the form. These will be written into the MyForm.designer.cs file. When you go into the code of your class you'll find within the constructor a method InitializeComponent(). Set the cursor on it an press F12. Here you can see what the designer has written into all the properties. You should respect the comment above the mentioned method and not start to modify the code with the code editor unless you really have understand how and when the designer will read and write code here (which is another chapter i can explain if needed). Otherwise it will happen that trying to opening your form with the designer after the code change will lead to an error message or code loss.
If you like to set some default value also, you should go back into the constructor and add the needed initialization code below the InitializeComponent() function and everything should work as expected.
Update
As you wrote in your comment you already know how the Designer interacts with the *.designer.cs file. So i really can't understand your concrete problem but maybe one of these articles can give you a more insight about how Microsoft wrote their components:
Make Your Components Really RAD with Visual Studio .NET Property Browser
Components in Visual Studio
This is very normal, since each time you are closing the form and opening it again you are having a new instance from the form MyPropsX, so the best way would be to save your properties in any kind of a database (sql, access, textfiles,...)
When I write code and need new property, i simply write propery name as it would exist already and choose action from menu:
Problem is, that it generates code like this:
protected int SomeNewProperty
{
get { throw new System.NotImplementedException(); }
set { throw new System.NotImplementedException(); }
}
So I need to go there and manually adjust that (actually I prefer to choose Create field from menu and change it to auto property). Anyway, I thought, may be there is a way to change default behavior of "Create property", that it would create auto property instantly?
Update
In Resharper 8 auto properties are available and may be set by default!
You cannot do this in R# (at least in v6). That is, create a pseudo property and have resharper generate the Auto Property stub.
You can still use the superior method that Visual Studio uses. Type out your new property which will show as a syntax error and then CTRL + . shows VS mini menu. Then just hit enter and straight away, the job is done.
It does not take you to the class file which can be distracting too. To use the shortcut above, you don't even need to have you cursor on the broken property name.
So this is better than the method described by Rickard as it is faster and less distracting you away from the code you are writing.
Just when you click Create property it will halt on the type. Hit tab and you will get a context menu with the option to use Auto property.
There is an option to change default body style.
However, the close you can get is
protected int SomeProperty
{
get { return 0; }
set { }
}
There is a default snippet that comes with Visual Studio called 'prop' Just type that, hit , give a type name and give it a name. Done and done.
I know that doesn't answer your question in terms of Resharper, but it is functionality already provided by the Visual Studio IDE.
Using the standard VS IDE, is there a fast way to create class properties that are linked to the local variables?
The class diagram seems to provide something, but it basically just created a property stub. Is there something better / easier out there ?
In VS.NET 2008 you can use refactoring, Encapsulate field (ctrl + r, e).
Here is info about how Refactoring In Visual Studio 2008
If you're talking about just making quick properties, then Auto-Generated properties are 'the bomb'. There's no need for a background local variable unless you plan to do something special in the get or set.
public string SampleProperty { get; set; }
or
public string SampleProperty { get; private set; }
Where you can optionally specify private / protected to limit the property to a setter or getter only. Then, you don't need a local variable and you just use the Property in place of the local variable. The compiler will generate the actual background variable for you.
I think you might be confusing an Auto Generated property with a property stub.
When building classes in Visual Studio (VS), you can generate property setters and getters quickly by defining a field variable, and then right-clicking on the field and selecting Refactor → Encapsulate Field from the popup menu. VS will display a dialog that lets you approve/change the property name, and optionally, preview changes. When you're satisfied, simply click OK. Voilà! VS generates the property!
By "generate", I mean auto-generation of the code necessary for a particular selected (set of) variable(s).
But any more explicit explication or comment on good practice is welcome.
Rather than using Ctrl + K, X you can also just type prop and then hit Tab twice.
Visual Studio also has a feature that will generate a Property from a private variable.
If you right-click on a variable, in the context menu that pops up, click on the "Refactor" item, and then choose Encapsulate Field.... This will create a getter/setter property for a variable.
I'm not too big a fan of this technique as it is a little bit awkward to use if you have to create a lot of getters/setters, and it puts the property directly below the private field, which bugs me, because I usually have all of my private fields grouped together, and this Visual Studio feature breaks my class' formatting.
I use Visual Studio 2013 Professional.
Place your cursor at the line of an instance variable.
Press combine keys Ctrl + R, Ctrl + E, or click the right mouse button. Choose context menu Refactor → Encapsulate Field..., and then press OK.
In Preview Reference Changes - Encapsulate Field dialog, press button Apply.
This is result:
You also place the cursor for choosing a property. Use menu Edit → Refactor → Encapsulate Field...
Other information:
Since C# 3.0 (November 19th 2007), we can use auto-implemented properties (this is merely syntactic sugar).
And
private int productID;
public int ProductID
{
get { return productID; }
set { productID = value; }
}
becomes
public int ProductID { get; set; }
By generate, do you mean auto-generate? If that's not what you mean:
Visual Studio 2008 has the easiest implementation for this:
public PropertyType PropertyName { get; set; }
In the background this creates an implied instance variable to which your property is stored and retrieved.
However if you want to put in more logic in your Properties, you will have to have an instance variable for it:
private PropertyType _property;
public PropertyType PropertyName
{
get
{
//logic here
return _property;
}
set
{
//logic here
_property = value;
}
}
Previous versions of Visual Studio always used this longhand method as well.
You can also use "propfull" and hit TAB twice.
The variable and property with get and set will be generated.
In visual studio 2019, select your properties like this:
Then press Ctrl+r
Then press Ctrl+e
A dialog will appear showing you the preview of the changes that are going to happen to your code. If everything looks good (which it mostly will), press OK.
If you are using Visual Studio 2005 and up, you can create a setter/getter real fast using the insert snippet command.
Right click on your code, click on Insert Snippet (Ctrl+K,X), and then choose "prop" from the list.
If you're using ReSharper, go into the ReSharper menu → Code → Generate...
(Or hit Alt + Ins inside the surrounding class), and you'll get all the options for generating getters and/or setters you can think of :-)
I created my own snippet that only adds {get; set;}. I made it just because I find prop → Tab to be clunky.
<?xml version="1.0" encoding="utf-8"?>
<CodeSnippets
xmlns="http://schemas.microsoft.com/VisualStudio/2005/CodeSnippet">
<CodeSnippet Format="1.0.0">
<Header>
<Title>get set</Title>
<Shortcut>get</Shortcut>
</Header>
<Snippet>
<Code Language="CSharp">
<![CDATA[{get; set;}]]>
</Code>
</Snippet>
</CodeSnippet>
</CodeSnippets>
With this, you type your PropType and PropName manually, then type get → Tab, and it will add the get set. It's nothing magical, but since I tend to type my access modifier first anyway, I may as well finish out the name and type.
In Visual Studio Community Edition 2015 you can select all the fields you want and then press Ctrl + . to automatically generate the properties.
You have to choose if you want to use the property instead of the field or not.
Use the propfull keyword.
It will generate a property and a variable.
Type keyword propfull in the editor, followed by two TABs. It will generate code like:
private data_type var_name;
public data_type var_name1{ get;set;}
Video demonstrating the use of snippet 'propfull' (among other things), at 4 min 11 secs.
In addition to the 'prop' snippet and auto-properties, there is a refactor option to let you select an existing field and expose it via a property (right click on the field → Refactor → Encapsulate Field...).
Also, if you don't like the 'prop' implementation, you can create your own snippets. Additionally, a third-party refactoring tool like ReSharper will give you even more features and make it easier to create more advanced snippets. I'd recommend ReSharper if you can afford it.
http://msdn.microsoft.com/en-us/library/f7d3wz0k(VS.80).aspx
Video demonstrating the use of snippet 'prop' (among other things), at 3 min 23 secs.
I don't have Visual Studio installed on my machine anymore (and I'm using Linux), but I do remember that there was an wizard hidden somewhere inside one of the menus that gave access to a class builder.
With this wizard, you could define all your classes' details, including methods and attributes. If I remember well, there was an option through which you could ask Visual Studio to create the setters and getters automatically for you.
I know it's quite vague, but check it out and you might find it.
On behalf of the Visual Studio tool, we can easily generate C# properties using an online tool called C# property generator.
First get Extension just press (Ctrl + Shift + X) and install getter setter ....
After this, just select your variable and right click. Go to Command palette...
And type getter ... It will suggest generate get and set methods. Click on this...
I personaly use CTRL+. and then select-
"Encapsulated Fildes".
That's a short for this option- (How can we generate getters and setters in Visual Studio?).
I marked the short for auto choosing refactoring (CTRL+. )
You just simply press Alt + Ins in Android Studio.
After declaring variables, you will get the getters and setters in the generated code.