Bernad Pakpahan Blog

Hi there,

Firstly, boxing and unboxing only occurs in value types, not reference ones. If your "Orders" type is class, not a struct, then you don't have to worry about it.

Secondly, I think the issue that you are aware of is about strongly typed collection. I'm suggesting that you use "BindingList" class for such purpose. BindingList is a generic class which is sufficient for your need. Accessing current object (strongly-typed one) can be attained by using indexer of your "[objectBindingList]" and the "[objectBindingSource].Position" property.

Thirdly, I'm not sure why you are using "Orders", which is plural for accessing a single object. I think it's a better idea to use "Order" for singular meaning and "Orders" for plural one, commonly a collection of "Order".

"Why .Net doesn’t fully support Generics?"
There is any wrong in your question..it should be "How do I write code fully support Generics". Remember .NET is A Framework, don't expect anymore.
About "your problem", you should build custom data binding that support Generics, it's the best solution!...If you have data source in Generics model then data binding provider should do that like it;)

Ok, that the solution using BindingList Class.
TList class whih is generics collection class, will be imlepementing BindingList. so my generic class will be supporting data binding. It's working! Thanks for Mr Mahara and Mr Agus.
But what happen?
I can't bind this object to BindingNavigator object, BindingNavigator only support BindingSource. Should I create custom Binding Navigator again? Or I make navigation control manually?

I Know the answer, it's should be ;).

For Mr Mahara, dont ask me why it's "orders" not "order". Please ask Microsoft, because it's a Norhtwind table in SQL Server 2000 :P. But may be I have the answers, Orders is not really single, because it is reference by orderdetails table. One Orders record can be have more than one detail item.

Bernard,

1. Purpose of Generics bukan utk avoid boxing & unboxing. Tp utk support "Parameterized Type" yg goal utamanya adalah strong typing dan capability polymorphism via template/generics. Performance benefit yg didapat "cuma" efek samping.

2. I guess you don't really understand what is CASTING and what is BOXING/UNBOXING.

BOXING adalah casting suatu value type ke reference type, UNBOXING adalah sebaliknya. Sedangkan jika casting dilakukan pd reference type ke reference type, tidak ada BOXING/UNBOXING yg tjd disitu. INi ada hubungannya dgn Value Type di store di Stack, sementara Reference Type di store di Heap. So, pd case kamu:

Orders order =(Orders) ordersBindingSource.Current;

This is NOT necessarily unboxing. It's just casting. Unless, Order is Value Type (struct, not class). But I'm sure it's a class, right? If you're using Struct for this, it's not a very good design then. So, BOXING/UNBOXING tidak terjadi di sini.

Coba explore lebih jauh tentang Value Type vs Reference Type dan juga Stack vs Heap. Jgn sampai salah menggunakan suatu terminologi. CASTING is NOT necessarily BOXING/UNBOXING. ;)

3. Your post title lebih tepat di buat:
"Why BindingSource doesn’t fully support Generics?". Karena .NET, down to CLR fully support Generics. Tidak spt VM Java misalnya yg menggunakan mekanisme erasure. So, yg gak support Generics itu cuma library itu saja (BindingSource). Why? Mungkin type tsb memang belum dibuat API generics-nya. ;) So, find another built in type yg support Generics or you can make one on your own.

Ok right now I know that boxing/boxing happen in value type or struct. Is casting still safe? Forget about boxing/unboxing, generics still important when we make strongly type collection, so error coz incompatible reference should be happen in compile time not in runtime.

May be I have choice the wrong title, but my concern is objectdatasource not fully support generics. I really happy when one of new features of .NET 2.0 is support object as data source. And with Visual studio 2005, you can do drag and drop programming without write complex code.

It will help some programmer especially UI programmer to develop application. Can you imagine when you drop an objectdatasource, you will be automatically create needed control with bindingsource and bindingnavigator. It's very helpful rather than previous development tool.

But what happen when technical leader, or architure ask for generics. objectdatasource wizard in Visual studio 2005 will be not useful. costum collection, custom binding, and custom navigator, and everything will be custom.

Microsoft try to convert complex programming become easy programming with his tool, something is very successfull, and something not really, But I know, a good programmer should be independent for all kind of tools.

Just for review, although I'm really satisfy with .NET 2.0 and Visual Studio 2005.

"I can't bind this object to BindingNavigator object, BindingNavigator only support BindingSource. Should I create custom Binding Navigator again? Or I make navigation control manually?
"
hehehehe...man, sepertinya kau belom dapat filosofi dari goal dari .NET terutama di OO. Kalau memang solusi standard component tidak sesuai dengan requirement mu maka .NET menyediakan opsi untuk exteded komponen tersebut atau buat baru yg implementasi dari Contact (interface) nya...so disini skill OO yang dipertaruhkan;)
Sayangnya dulu kita jarang diskusi waktu kantor lantaran kita blom pernah satu project;)

Hehehehe iya deh Boss....
Gw tau banget "Nggak ada yang nggak bisa di dunia programming". If you can't use standard library you can make your own. Makanya gw bilang "I Know the answer, it's should be ;).". Di kantor yang baru gw belajar banyak tentang itu. Bahkan boss gw udah create type query yang mau nyaingin LINQ. Try to become OO geek. hehehehehe

Hehehe, kemarin mau post feedback disini tapi error (kebanyakan orang yg mau komentar kali)...but dont worry, nggak usah malu kalo salah, toh banyak yg nuntun ke jalan yg benar :)

Wah, si Om Wok mau bikin LINQ sendiri? Tuh orang harusnya kerja di Redmond :)

>> I can't bind this object to BindingNavigator object, BindingNavigator only support BindingSource. Should I create custom Binding Navigator again? Or I make navigation control manually? <<

I'm not sure enough about what you are really doing with the BindingSource and BindingList. I think you should just bind your BindingSource's DataSource property to your BindingList's object and bind your BindingNavigator's DataSource property to your BindingSource's object. It should just work fine.



>> For Mr Mahara, dont ask me why it's "orders" not "order". Please ask Microsoft, because it's a Norhtwind table in SQL Server 2000 :P. But may be I have the answers, Orders is not really single, because it is reference by orderdetails table. One Orders record can be have more than one detail item. <<

There has been an issue with naming a table, whether it should be singular and plural one. One is better to use a singular one. Referring to Northwind (a database sample provided for MSSQL 2000), you may find that it still uses a plural one. But if you see the latest database sample provided in MSSQL 2005 (Adventure Works), Microsoft has already used a singular table name (except for BillOfMaterials). The reason is simply because it's just an entity.

My Man Mahara, there is no issue with Northwind or SQL Server 2000. You say every naming method in table must be singular, coz all table are entity. Maybe I agree with you. But please change your point of view, SQL Server 2000 has been realeased before .NET 1.0 and the most important thing SQL Server is RDBMS event SQL Server 2005 also RDBMS. If you are classic VB programmer or other Non OO programmer, I think doesn't matter with orders table name.

It's different if your database is OO database like db4o, everything must be OO taste. So no issue with Northwind database, coz it's sample database for all programming language. I know I use this database for OO programming, but it's a bad idea if I must change the table name in database or in my code (just for dummy my friend).So my asnwers should be clear. Btw, thank you for your comment.

Frans Bouma (C# MVP) also found similar issues with me. See this issues in his blog
http://weblogs.asp.net/fbouma/archive/2005/12/23/433899.aspx

Nice Article and Site, Booked for Reference

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