C# 3.0: I love object and collection initializers

re: C# 3.0: I love object and collection initializers

Patrick — Sat, 17 Sep 2005 19:59:59 GMT

Ok, now this I like! Forget lambda functions, continuation, and all that other jazz. This is a feature that will save keystrokes, that is intuitive, and that instantly makes sense to all C# developers!

Let's see more stuff like this that everyone can benefit from!

re: C# 3.0: I love object and collection initializers

jeff — Sat, 17 Sep 2005 20:27:28 GMT

This looks cool, though is it just limited to public fields? Setting properties would be nice.

Does this only work if there is no default constructor for an object?

re: C# 3.0: I love object and collection initializers

tzagotta — Sat, 17 Sep 2005 20:36:44 GMT

This is a really nice addition!

It would be nice to get a CTP preview release add-in for VS2005 for some of these C# 3.0 features. It will be too hard to wait 2-3 years until the next release!

re: C# 3.0: I love object and collection initializers

Victor — Sat, 17 Sep 2005 21:08:37 GMT

The collection initializer is nice, but you can do something similar in C# 2.0 with only a little bit more work. For example, your sample would look like:

List<int> digits = new List<int> (
new int[] { 0, 1, 2, 3, 4, 5, 6, 7, 8, 9 });

re: C# 3.0: I love object and collection initializers

CN — Sat, 17 Sep 2005 22:35:03 GMT

Am I correct in assuming that any "readonly" fields will not be accepted in the initalizer, as I guess it's just syntactic sugar? This means you'll still need the different constructors for types where it has to be immutable, for example simple struct containers, where this would otherwise be a very nice syntax.

re: C# 3.0: I love object and collection initializers

zz — Sun, 18 Sep 2005 01:52:46 GMT

What happens when Customer does not have a default constructor. Does it allow something like this?

var cust = new Customer( init1, init2 ) // <- Non-default constructor
{name = "Abhinaba Basu", address = "1835 73rd Ave NE, Medina, WA 98039", Age = 99 };

re: C# 3.0: I love object and collection initializers

abhinaba — Sun, 18 Sep 2005 13:01:45 GMT

The answer to each of the questions above

Q. Are properties supported (Jeff)
A. Yes they are. To illustrate this I specifically added Age as a property in Customer class

Q. Does this only work if there is no default constructor for an object (jeff)
A. This has nothing to do with presense of ctor. Lets see the following example where there is a ctor and you invoke both the ctor as well as use the initializer syntax

class Item
{
private int m_itemId;
private string m_itemName;

public Item(int itemId, string itemName)
{
m_itemId = itemId;
m_itemName = itemName;
}

public string description;
}
Item item = new Item (12, "Football") { description = "Size 4 footbal" } ;

Q. C#2.0 (or 1.0) already had some thing like
List<int> digits = new List<int> (
new int[] { 0, 1, 2, 3, 4, 5, 6, 7, 8, 9 }); (victor)
A. Well yes, this is ok with value types. For reference types you can allocate the objects and then add them in one statement, either as above or using List<>.AddRange. But you had to manage the intermediate variables to store inidividual items. There was no way to do the whole thing in one statement. So effectively with this new syntax value and reference type collection initialization is becoming the same.

Q.Does it work with Readonly fields (CN)
A. You are right this is just syntactic sugar and hence will not work with readonly fields.

Q. What happens with non-default ctor (zz)
A. You are absolutely right it works just as you thought. See the sample in this comment

Thank you

Great blog — Thu, 23 Feb 2006 00:57:18 GMT

Your blog is really very interesting.

re: C# 3.0: I love object and collection initializers

Samuel — Wed, 19 Apr 2006 15:02:06 GMT

This just looks like a crippled version of the VB "With" syntax. Its really bad the C# programmers had to live without stroke savers like this so long ....

re: C# 3.0: I love object and collection initializers

mhp — Thu, 20 Apr 2006 15:52:54 GMT

For those who has worked with VB will find this feature still incomplete. If we are talking about C# 3.0 you should seriously consider implementing "With" keyword as supported in VB. In that case C# 3.0 code may look like following:

With (customer = new Customer()){
.name = "Abhinaba Basu";
.address = "1835 73rd Ave NE, Medina, WA 98039";
.Age = 99;
}

IMHO, the feature you described does very little as far as readability has cocerned, beside that it only supported in constructor. However if you implement "With" keyword, it will have more than one advantages:
1. You can use it anywhere (not limited to constructor)
2. CLR/JIT can omptimize performance
3. More readable

re: C# 3.0: I love object and collection initializers

Kazi — Fri, 21 Apr 2006 18:10:27 GMT

The collection initializer is not working with Dictionary<TKey, TValue>, any chance for a fix?

re: C# 3.0: I love object and collection initializers

abhinaba — Fri, 21 Apr 2006 21:23:55 GMT

Kazi, can you post any code snippet of what exactly is not working? I'll try to get you an answer

re: C# 3.0: I love object and collection initializers

Kazi — Sat, 22 Apr 2006 15:36:38 GMT

A simple sample for generic Dictionary objects trying to initialize with collection initializers (compiler error messages inculded):

// Error: Cannot implicitly convert type 'string' to 'System.Collections.Generic.KeyValuePair<string,int>'
var dict1 = new Dictionary<string, int>() {"one", 1};

// Error: No overload for method 'Add' takes '1' arguments
var dict2 = new Dictionary<string, int>() {new KeyValuePair<string, int>("one", 1)};

C# Anonymous methods, lambda expressions and Ruby

I know the answer (it's 42) — Wed, 23 Aug 2006 20:10:06 GMT

In my last post&nbsp;I had discussed about anonymous methods.
I had used the following code snippet...

re: C# 3.0: I love object and collection initializers

MZ — Tue, 26 Sep 2006 17:56:49 GMT

I got here looking for information similar to CNs... and am dissappointed. Are there any plans to make "immutable" objects less painful?

Right now there is no easy way to say "Copy X but with changed properties X.A and X.B". Being able to designate a field or property as "Initializable" instead of "ReadOnly" to allow immutable functionality would make things less painful.

Imagine being able to say

myFont = new Font(myFont){Size = 8}

instead of

myFont = new Font(
myFont.FontFamily,
8,
myFont.Style,
GraphicsUnit.Point,
myFont.GdiCharSet,
myFont.GdiVerticalFont
);

Theoritically one can do similar functionality with tons of heavily overloaded codegenned constructors, but even that falls apart if you have multiple properties with the same type.

Orcas - Sept CTP « Tales from a Trading Desk

Orcas - Sept CTP « Tales from a Trading Desk — Sat, 07 Oct 2006 01:21:21 GMT

PingBack from http://mdavey.wordpress.com/2006/10/06/orcas-sept-ctp/

explicatory Lille

explicatory Lille — Wed, 22 Nov 2006 05:34:30 GMT

This is the my fourth post in the series of posts I am making on C#3.0. See the previous posts here, here and here

I do not agree. Go to http://www.hotelsstore.info/liar_France/ocellus_Nord%20Pas%20de%20Calais/explicatory_Lille_1.html

Collection initializers are a terrible idea

David — Thu, 11 Jan 2007 00:40:04 GMT

I have posted an article on why collection initializers are a terrible idea at http://commongenius.com/articles/archive/2006/12/07/Collection-Initializers-and-Duck-Typing.aspx

re: C# 3.0: I love object and collection initializers

Matthieu MEZIL — Thu, 22 Feb 2007 17:01:46 GMT

For tabs, you can do this

int[] tab = { 1, 2, 3};

dobbin Florence

dobbin Florence — Thu, 22 Mar 2007 13:18:32 GMT

This is the my fourth post in the series of posts I am making on C#3.0. See the previous posts here, here and here

I do not agree. Go to http://www.greatjobz.info/bronchi_Italy/invulnerability_Toscana/dobbin_Florence_1.html

the rasx() context » Blog Archive » The Predicate Delegate

the rasx() context » Blog Archive » The Predicate Delegate — Tue, 11 Sep 2007 22:51:52 GMT

PingBack from http://www.kintespace.com/rasxlog/?p=738

How not to use ASP.AJAX - Pt 2

.NET Playground — Fri, 16 Nov 2007 01:34:18 GMT

How not to use ASP.AJAX - Pt 2

Neues .NET 3.5 Feature: Collection Initializers

Jürgen Gutsch — Tue, 20 Nov 2007 22:36:26 GMT

Noch mehr Schreibarbeit spart man zusätzlich mit den Collection Initializers, die so ähnlich wie die

C# Anonymous methods, lambda expressions and Ruby

I know the answer (it's 42) — Thu, 22 Nov 2007 15:29:43 GMT

In my last post I had discussed about anonymous methods. I had used the following code snippet to show

Dictionary with Collection Initializer

RNEELY — Mon, 12 May 2008 21:29:05 GMT

Kazi, Try this:

static void Main(string[] args)

{

Dictionary<string, int> MyMap = new Dictionary<string, int>()

{ { "one", 1 }, { "two", 2 }};

Console.WriteLine("one is {0}", MyMap["one"].ToString());

Console.WriteLine("two is {0}", MyMap["two"].ToString());

}

re: C# 3.0: I love object and collection initializers

ajay_ndelhi — Fri, 20 Jun 2008 21:16:20 GMT

Thank for putting it so nicely.

re: C# 3.0: I love object and collection initializers

Spike — Sat, 13 Dec 2008 02:18:18 GMT

QUOTE ----------------------------------------

Saturday, September 17, 2005 1:27 PM by jeff

This looks cool, though is it just limited to public fields? Setting properties would be nice.

----------------------------------------------

Idiot, read the article first, before you post next time.

Third line:

QUOTE -----------------------------------------

if I wanted to create a object of the type customer and fill up the public VARIABLES and P R O P E R T I E S then in C#2.0 I need to do something like....

----------------------------------------------

re: C# 3.0: I love object and collection initializers

Furqan Khan — Sat, 13 Dec 2008 02:21:18 GMT

HAHA! Yes, you are pretty stupid to ask that question. The article shows you in the first line of the first code example how to make it work for properties.

lol@u wtf