Every SERIOUS VB6 application, ended up requiring
that you import some functionality from the windows API or another DLL.
However if you were looking for a .NET equivalent and
google did not take you to the right page,
there is a document (a little old I might say)
called
Microsoft Win32 to Microsoft .NET Framework API Map
I remember a couple of other pages that were even more complete,
but right know I can only remember
http://pinvoke.net that gives some info about APIs
In the VB world previous to .NET a concept you probably had to deal with was
TWIPS.
What were Twips? Well if you do not remember those happy VB6 times, let me
refresh your memory:
Twips are screen-independent units to ensure that the proportion of screen
elements are the same on all display systems.
A twip is defined as being 1/1440 of an inch.
A Pixel is a screen-dependent unit, standing for 'picture element'.
A pixel is a dot that represents the smallest graphical measurement on a screen.
In .NET everything is pixels. So if you migrated something from VB6 using the
Upgrade Wizard you might found several expressions like:
VB6.TwipsToPixelsX(ctrl.Left)
or VB6.PixelsToTwipsY(ctrl.Height)
There is an X and a Y version of this function, because the conversion factor
is not the same for both axis.
Sadly you can even found some expressions like:
VB6.TwipsToPixelsX(VB6.PixelsToTwipsX(ctrl.Left))
In a strict sense there could be minor differences because of the conversion
factors. But in it seams that things like that can be removed because all
controls Bound properties like Left, Top, Bottom, Right are in pixels. So why
will you convert your pixels units to Twips units to then convert them back to
Pixels if they where already in Pixels????
Also you can find something like:
VB6.TwipsToPixelsX(ctrl.Left + ctrl.Width + 30) which should be something
like:
ctrl.Left + ctrl.Width + VB6.TwipsToPixelsX(30)
If you have an application migrated with the Upgrade Wizard you can use some
regular expressions to improve those expressions. If the conversion is something
like:
VB6.TwipsToPixelsY(VB6.PixelsToTwipsX(ctrl.Left)) then be careful because
conversion factor might produce a different value, due to the change of axis.
jeje Or you can uset the VBCompanion, the extensible version of the Upgrade
Wizard!!!
.NET has a more strict typing than VB6
So you must check in some circumstances if your object implements an interface
or not.
So I had used the as and is operators in C# but I did not know
how to do that.
I did I little research and I discovered some things about casting operators for
VB.NET
| Operator |
Example |
Observations |
| CType |
Dim testNumber
As Long
= 1000
' The following line of code sets testNewType
to 1000.0.
Dim testNewType
As Single
= CType(testNumber, Single)
|
Throws InvalidCastException or OverflowException It could
be less eficient due to VB.Net helper routines.
This is a Narrowing and Widening operator.
It can be overloaded
Public
Structure digit
Private dig
As Byte
Public
Sub New(ByVal
b As Byte)
If
(b OrElse b > 9)
Then Throw
New _
System.ArgumentException("Argument outside
range for Byte")
Me.dig
= b
End
Sub
Public
Shared Widening Operator CType(ByVal
d As digit)
As Byte
Return
d.dig
End Operator
Public
Shared Narrowing Operator CType(ByVal
b As Byte)
As digit
Return
New digit(b)
End Operator
End Structure
|
| DirectCast |
Dim f
As New
System.Windows.Forms.Form
Dim c As
System.Windows.Forms.Control
' The following conversion succeeds.
c = DirectCast(f,
System.Windows.Forms.Control)
|
Throws InvalidCastException. Is more
efficient than CType because it does not depend on the Visual
Basic helper runtime functions. It can even detect some errors as
invalid casts during compile time
However it requires a relationship of inheritance of implementation
For example:
Dim q As
Object = 2.37
Dim i As
Integer = CType(q,
Integer)
' The following conversion fails at run time
Dim j As
Integer =
DirectCast(q, Integer)
The run-time type of q is Double. CType
succeeds because Double can be converted to Integer.
However, the first DirectCast fails at run time because the
run-time type of Double has no inheritance relationship with
Integer, even though a conversion exists
|
| TryCast |
Dim
obj As MyType = TryCast(obj, MyType)
If obj
Is Nothing
Then
' Object could not be cast
Else
' Object was casted
End If |
Throws no exceptions. |
All this information has been taken from the MSDN site. This is just a quick
summary. For more information see:
Type Conversion Functions
Conversion Functions (Visual Basic)
Widening and Narrowing Conversions
Implicit and Explicit Conversions
This is a nostalgic note. Someone asked me, "hey, how do you make a fixed len
string in VB6?"
As the computer geek that I am, that the kind of questions I like to be able to
answer.
These are important questions like all those questions from the 80's rally:
The name of all the original thundercats...
The planet where Luck Skywalker went to learn with Yoda...
Which Star Trek character appear in ALL the episodes (yes it is Spock, Kirk is
not in all of them)
Well, the thing is to define a fixed len string in VB6 you do something like:
Dim aString As String * 10
If you do something like:
aString = "Mau" ' aString ==> "Mau "
That's all
Fixed length strings are automatically filled with spaces to pad them to their
fixed-length. How do you get rid of the extra spaces? Duh!!! with RTrim$ don't
you remember
When a variable like aString is declared, it will be filled with Null characters
until it is used.
And yes functions (RTrim$, LTrim$, and Mid$) will not trim Null characters, so
be sure to assign it with an empty string "" immediately.
Ahh! and by the way when you translate that to .NET, .NET does not have a fixed
len string so the easiest thing to do is use:
Microsoft.VisualBasic.Compatibility.VB6.FixedLengthString.
[C#]
using Microsoft.VisualBasic.Compatibility;
...
void foo()
{
VB6.FixedLengthString aString = VB6.FixedLengthString(10, "Mau");
}
As any geek I live frustrated by the lack of good tools in Windows.
Notepad, and Paint are just a couple of examples.
I was just dreaming for a nice, light replacement for those applications.
Well, recently somebody wrote a nice page with amazing freeware that you can use:
Amazing Tools
Localize a VB6 application can be cumbersome, specially if it was not even originally planned to be localized.
Nowadays is common that you're clients might demand support for different languages.
While a localization task is still difficult, we have found excellent results performing it during a VB Migration.
Our tools allow us to easily externalize all your strings. After that the traslation task becomes easy, and you can even use the help
of nice projets like
Automatically Translate your .NET resource files with Google Translate
These project extends the VB and C# languages with query,
set and transforms operations. It adds a native syntax for those operations.
The idea of the LINQ project is to make data manipulation
part of the language constructs. Lets see these VB examples for LINQ:
The following examples
associates the Customer class to the Customer table. Just adding the Column Tag
before a field, maps it to a table column.
<Table(Name:="Customers")>
_
Public Class Customer
<Column(Id:=True)>
_
Public
CustomerID As String
…
<Column()> _
Public City As String
…
End Class
To
access the database you do something like:
'
DataContext takes a connection string
Dim db As
DataContext = _
New
DataContext("c:\...\northwnd.mdf")
'Get a typed table to
run queries
Dim Customers As
Table(Of Customer) = db.GetTable(Of Customer)()
'Query for customers from London
Dim q = _
From
c In Customers _
Where
c.City = "London" _
Select c
For Each cust In q
Console.WriteLine("id=" & Customer.CustomerID
& _
",
City=" & Customer.City)
Next
You just create a
DataContext and create typed object that will relate dot the relational tables.
I think this is awesome!!
It is even nicer if you
create a strongly typed DataContext
Partial Public Class Northwind
Inherits DataContext
Public
Customers As Table(Of
Customer)
Public
Orders as Table(Of
Order)
Public Sub New(connection As String)
MyBase.New(connection)
Your
code gets cleaner like the following:
Dim db As New
Northwind("c:\...\northwnd.mdf")
Dim q = _
From c In db.Customers _
Where
c.City = "London" _
Select
c
For Each cust In q
Console.WriteLine("id=" & Customer.CustomerID
& _
",
City=" & Customer.City)
Next
These project will start a
lot of exciting posibilities. I recommed you have a look at’: http://msdn.microsoft.com/data/ref/linq/
Ok enough theory. To start using the internationalization
stuff lets start with a simple Form.
Open the Visual
Studio IDE. And Start a Windows Forms project. And then create a simple Form.
Add some labels and buttons and set their captions. Once you do that and finish
the initial creation of the form, go to the properties pane and change the
Localizable property to true and
assign the desired value in the Language property. The Visual Studio designer
will save the changes in additional resource files whose names will look like
<FormName>.<culture>.resx
Once you finish the texts, sizes, positions for the first
culture and save it. The IDE creates the resource file for that culture. If you
want to create a resource file for another language just change the Form
property and assign the text for this new language.
You can not only assign personalized translations for each
region but also the position and size of components. This is useful because in
some languages the buttons might need to be bigger because the labels could be
bigger.
All this work is supported by the .NET resource managers. System.Resources.ResourceManager class.
I recommend you also using String Resource Tools like the
ones at: http://www.codeplex.com/ResourceRefactoring
These tools makes it even easier the task of moving all your
strings to resource files:
Recently I was asked by some fellows some help to make a new
version of their VB6 application in Spanish, but at the end we end up migrating
the application to VB.Net and taking advantage of the .NET internationalization
features.
VB6 did not provided and out-of-box support for multiple
cultures, but the .NET framework provides the developer with utilities to
create applications that allow users in multiple regions use their applications
according to their “Culture”.
The .Net Framework is able to handle different cultures.
These “cultures” are used to localize certain aspects of the application for
particular geographic zones.
When an application is not created with any cultural
considerations it is said to use a Neutral
Culture. It implies that independent of the machine configuration it will
behave and display components in the same way.
The Culture is assigned automactically using the machine
settings or it can be altered programmatically. You can use the property
System.Globalization.CultureInfo.CurrentUICulture for that purpose.
Cultures have two elements: language and region. For example
for Argentina where Spanish
is spoken la culture will be es-AR (es is for Spanish: ESpañol and AR for Argentina)
If no information is found at all for an language then the
neutral culture is used.
The information for user display is handler in assemblies
usually called “satellite assemblies” which are loaded depending on the culture
of the environment where the application is executed.
This is a very controversial topic. Recently I have seen several blogs that state that the VB6 Programmers are moving to other platforms like PHP or Java instead of VB.NET
For example see:
Number of VB
Developerts Declining in US
By
Steve Graegert
“They’re also leaving VB.NET; which is down by 26%. This means Java
now holds the market penetration lead at 45% (with developers using Java during
some portion of their time), followed by C/C++ at 40%, and C# at 32%.”
I also remember an Article I read in 2005 in JDJ (Java Developers Journal) that expressed that C# was a language created similar to C++ to aid the C++ programmers move to the .NET Framework, argument that I do not share.
I have no evidence but I do not feel that it is that way. I'm am a Java Developer too. And both platforms have their merits. C# is a nice language, very similar to Java and C++ no doubt but it deserves its own place. Visual Studio has still a path to follow. But VS2005 provides some useful refactorings and the incredibly awaited feature that allows you to edit the code that you're running :)
Maybe the 1.0 and 1.1 frameworks were not enterprise ready, but 2.0 and 3.0 frameworks are an excellent improvent.
Java as well had to go thru a lot of JDK releases. They have just released the 1.6 and what about the J2EE releases, the Java Enterprise Beans fiasco. You can confirm that by looking at the rise of POJO (Plain Old Java Object) frameworks like spring.
In general everything requires time to grow. I think that Java has been more time in the market and it has finally provided mechanisms that allow the development of enterprise services "easier" and it is giving it momentum.
.NET components industry is common, there are lots of components and somethings are easier. So I'll wait some time, maybe a couple of year to really find out which is the hotter platform.