Great SQL Server Error

~ chriseyre2000 ~ Leave a comment
When attempting to:

ALTER TABLE MYTABLE ALTER COLUMN TIMESTAMP varbinary(8) NULL

The following error is raised:

Cannot alter column ‘TIMESTAMP’ because it is ‘timestamp’.

You have to do the following:

ALTER TABLE MYTABLE DROP COLUMN TIMESTAMP
ALTER TABLE MYTABLE ADD TIMESTAMP varbinary(8) NULL

What is a Non-CLS Compliant Exeception and why should I care.

~ chriseyre2000 ~ 2 Comments
While studying for Exam 70-316 (Developing and Implementing Windows-based Applications with Visual C#.NET and Visual Studio.NET) I found that the .NET framework has what is known as a “Non-CLS compliant exception”

While investigating this I found the following article on how to implement a bulletprof main routine:

    Sample of how to implement the main routine of an application.

Pop Quiz for Delphi developers : what is the most basic class that can be thrown as an exception?
The obvious answer of Exception is wrong – you can raise a TObject or descendant (TForm?)- just don’t expect your exception handers to work.

The .NET CLR has this great base Exception class.
So why do they need to allow anything else!
Why not define a ENonCLSException descendant and raise that!

It appears that IL allows a System.Object to be thrown in exactly the same way as Delphi!
The above link includes a sample of how do do this.

The moral of this tale is that your default exception handler needs to finish with a generic catch clause. I need to look into how to add my own template application to the defaults in VS.NET – some of these need to be created by default.

More usability issues

~ chriseyre2000 ~ Leave a comment
The .NET TextBox class when set to multi-line is a very weak control compared to Delphi’s rich TMemo control. TMemo exposes a Lines property to which a line of text can be simply added r individual lines manipulated. I need to look at the TStringList for C# to see if I can use it to create a fully featured TMemo for .NET.

            textBox2multiline.Text += System.Environment.NewLine + “This is a test”;

is far more code (and far less obvious) than:
 
             memo1.lines.Add(‘This is a test’);

In addition when you rename a delphi control if the text property matches the control then the text property changes as well. I wonder if the designer could be extended that far? This makes editing controls much easier – first you rename them and then you customise that into the correct text. This is far more efficient.

Replacement for ShellExecute

~ chriseyre2000 ~ Leave a comment
Try using:

System.Diagnostics.Process.Start

This is much cleaner than the PInvoke version of:

[DllImport(“shell32.dll”)]
public static extern int ShellExecute(IntPtr hWnd,
            string lpszOp, string lpszFile,
            string lpszParams, string lpszDir,int FsShowCmd);

static void Main(string[] args)
{
int hWnd;
long noth;

ShellExecute(0, “OPEN”, @”D:\WINNT\NOTEPAD.EXE”,
null, null, 0);

}

Useability issues

~ chriseyre2000 ~ Leave a comment
One of the reasons why Borland products tend to score above the microsoft equivalents is in the area of  small usability touches.

The .NET Framework has a LinkLabel control. The purpose of this is to allow hyperlinks &c.
However there is no desgner for this. You have to add the associated links in code.
While this is flexible it is more difficult than necessary to use for the simple case. Borland would have implemented the designer here.

Borland’s big problem has been marketing and sales.  Even when they have a superior  product they  cannot get the market to accept it.  Of late they seem to be diversifying into earlier stages of the lifecycle – requirements (CaliberRM), design (Together and Bold) and configuration/planning (StarTeam). It is difficult to complete against the Microsoft Universal licence (allowing access to almost all the development tools for a fixed annual fee) – Microsoft make their money off of the server products that the customers require. Borland could launch a product as a Visual Studio extender – adding in the missing property editors.