Re: GWorkspace openFile & ImageViewer

[Richard Frith-Macdonald]

Marko Riedel wrote:

> I looked at NSWorkspace.m and its use of _launched (dictionary).
>
> 1. NSWorkspace invokes _connectApplication in order to open a file.
Yep.

> 2. It seems it is looking for a named port (application name minus
>   extension) to talk to the application. Does NSApplication implement
>   this, i.e. does it listen on this port? What sort of messages
>   (selectors) can be invoked over this type of connection?
Yes, NSApplication does implement it, and you can send things like 
-application:OpenFile:
to it.

> 3. I guess that the current implementation never establishes a
>   connection. NSWorkspace then launches the application with the file
>   as a command line argument (line 442). This explains why it launches
>   the same application more than once, i.e. one for every file.
That's a good hypothesis ... but it works on my system, so you may have 
some system specific trouble.

> 4. NSWorkspace consults _launched, but the code shows that the
>   contents of this dictionary do not affect which app
>   _connectApplication returns.
Yes.  The _launched information tells us what apps were launched when, 
so if an
app is not responding we can tell if it has hung (was launched a while 
ago), or is still in
the process of starting up.

> Maybe we should implement listening behavior in NSApplication?
Already there (controlled by the GSServicesManager class).

> This
> would make _launched superfluous,
Not so ... _launched should have nothing to do with this.

> at least where opening files are
> concerned. If there is an app at the named port, message it, else
> launch it, then message.
That's the way it works now ... launched is there mostly to stop us 
launching lots of instances of an app just because it's slow in starting 
up and responding to messages.