Re: Writing a simple function in C#

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On May 26, 4:59 am, Jon Harrop <j...@xxxxxxxxxxxxxxxxx> wrote:
Moty Michaely wrote:
Use the Command Design Pattern to encapsulate lot's of parameters.

Can you elaborate on this?

I've read this description of the pattern:

http://www.exciton.cs.rice.edu/JAvaResources/DesignPatterns/command.htm

and I can't see how it is relevant. Is this for when you have a set of
optional arguments that are common to several different functions?

--
Dr Jon D Harrop, Flying Frog Consultancy
The F#.NET Journalhttp://www.ffconsultancy.com/products/fsharp_journal/?usenet

Hi,

When you need to pass common arguments (not necessarily optional) you
can encapsulate the arguments with a class and implement a function in
that class..

For example (very simple one, you can always elevate it to much more
complex one):

To copy a file we can do this:
void CopyFile(string src, string dest)

Or we can encapsulate the CopyFile operation to a FileOperation class:

class FileOperationContext
{
string source;
string destination;

public FileOperationContext(string source, string destination)
{
this.source = source;
this.destination = destination;
}

}

abstract class FileOperation {
FileOperationContext context;

public FileOperation(FileOperationContext context)
{
this.context = context;
}

void Operate();
}

class FileCopy : FileOperation
{
public FileCopy (FileOperationContext context) : base(context)
{ }

override Operate() {
System.IO.File.Copy(context.source, context.destination);
}
}

You can of course not implement methods and just use the class as an
argument list..
for example:

void CopyFile(FileOperationContext context) {
System.IO.File.Copy(context.source, context.destination);
}

void MoveFile(FileOperationContext context) {
System.IO.File.Move(context.source, context.destination);
}

etc....

Hope this clears things up.. =)

Moty

.

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