ElanHasson.com

Here's a question from a customer:

I made some changes related to my shell extension [details omitted],
but the changes don't show up in the Explorer
window when I refresh it.
Any suggestions on how to solve this problem?

When we asked how they were refreshing the Explorer
window, we were expecting something like pressing F5
or calling SHChangeNotify with
SHCNE_UPDATEDIR,
or maybe calling IShellView::Refresh
or possibly even
calling WebBrowser.Refresh from script.
But we definitely didn't expect this response:

I'm invoking the

Process.Refresh()
method from the

System.Diagnostics
namespace.

Just because a method is called
Refresh
doesn't mean that it refreshes what you want.
I think this is somebody who just
saw a method name,
perhaps

inspired by IntelliSense
and—

Boom! You have it!—assumed
it did what was needed without actually reading
the documentation to check.
But you don't even need to read the documentation to know that
Process.Refresh has no chance of working.

Since it's a method on the Process class,
the method is applicable to all processes.
But certainly there is no generic way to tell a process to refresh.
This magical Refresh method would have to know how to
refresh Explorer windows,
Firefox web pages,
iTunes mp3 tags...
And what would it even mean to refresh, say, a Notepad window?
Does that mean to throw away all changes and reload the original document?

How do you know that there is no generic way to tell a process to refresh?
Well, for one thing, a single process like Explorer can be viewing
multiple objects that can be refreshed; which one are you refreshing?
Second, when you write your own program, how do you implement refresh?
Do you respond to some standard system Refresh message?
Or do you just add a Refresh option to your program's main menu
and give it some arbitrary command ID?
If there's not even a standard way to refresh your program's window,
then how can there be a standard way to refresh all program windows?

In this specific case, the Process.Refresh method
refreshes the Process object's internal cache of process
properties.
It doesn't actually do anything to the process itself.
How could it?

It's like

thinking that the Matrix.Rotate method
rotates the entries in a matrix.

Epilogue

Actually, I'm scared by this customer's question for another reason:
The fact that they even mentioned Process.Refresh
suggests to me that they wrote their shell extension in managed
code, which we already know

is strongly disrecommended.