Month: May 2005

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.