From: Lyle Johnson <lyle@...>
Date: 2003-05-05T23:58:08+09:00
Subject: Re: Problem using FXFileStream

Thomas Stammeier wrote:

> I'm having problems using FXFileStream in FXRuby. I want so save an 
> FXImage using the "save" method. Here's the piece of code:
> 
>  FXFileStream.open ("test.jpg", FXStreamSave) do |stream |
>      img.savePixels(stream)
>  end
> 
> This actually works, but the file is not closed until I quit the 
> application. After "end" the file is still open and no data has been 
> written to it. When I quit the application the file is a valid .jpg 
> file. Is this a bug or is there anything wrong with my code?

I don't see anything wrong with your code, but I also don't understand 
how you could be seeing the behavior you describe. For reference, here's 
the code that implements the FXFileStream.open singleton method (from 
lib/fox/iterators.rb):

     def FXFileStream.open(filename, save_or_load, container=nil)
       fstream = FXFileStream.new(container)
       status = fstream.open(filename, save_or_load)
       if block_given?
	begin
           yield fstream
	ensure
	  fstream.close
	end
       else
         fstream
       end
     end

When you use FXFileStream.open as shown, there's an 'ensure' block that 
closes the file stream (and this calls the standard C library's fclose() 
function under the hood). The only possible problem I see (and one I 
should account for) is that FXFileStream#open (the instance method) 
returns some kind of error code. But if that were to happen, I don't 
think that call to FXImage#savePixels would have any effect, i.e. you 
wouldn't end up with a valid JPEG file at the end.

Lyle