[IPython-dev] connecting ipythonqt to an existing kernel should not require specifying 4 ports

[Evan Patterson]

On Thu, Sep 9, 2010 at 5:32 PM, MinRK <benjaminrk at gmail.com> wrote:
>
>
> On Thu, Sep 9, 2010 at 17:21, Evan Patterson <epatters at enthought.com> wrote:
>>
>> On Thu, Sep 9, 2010 at 3:58 PM, MinRK <benjaminrk at gmail.com> wrote:
>> > Hello,
>> > In order to connect a second ipythonqt frontend to an existing kernel, I
>> > must specify by hand all 4 ports at the command-line.  This really
>> > shouldn't
>> > be the case, especially since the default behavior is to have the ports
>> > ordered sequentially.
>>
>> That may be the default behavior of your OS, but that's not the
>> default behavior in general. Random port is selection is currently
>> left entirely up to the OS (as it should be), and on some systems this
>> means that you get ports that appear to be totally random.
>
> Good point, that makes a two-stage connect even more important, since you
> can't expect the relationship between the port numbers to be well behaved.
>
>>
>> Guaranteeing that the ports are in consecutive order requires ugly
>> code (a while loop that keeps binding a port until you find one that
>> has three consecutive ports that are also open). Frankly, I think that
>> if you care what the ports are, you should just pass them when
>> launching the kernel in the first place.
>
> The problem is not that I care what the ports are, quite the opposite. I
> don't want to care what the ports are, but the current state requires me to
> track a new set of 4 every time. This is quite unpleasant for launching
> multiple clients on a kernel, in addition to being unnecessary.
> It should be very easy to connect additional clients to a running kernel,
> and specifying every port by hand does not qualify.
> $> ipythonqt -e
> should successfully connect to a kernel started with:
> $> ipythonqt
> At the _very worst_, a single port (or file) should have to be specified to
> connect to a kernel launched with defaults.
> This can be done, as it was in Twisted code, via a file in IPYTHON_DIR, or
> even better with a two-stage connect.

I see your point; something does have to be done about this. That
being said, it's important to keep in mind that ipythonqt is currently
not so much an application as a tech demo, so there are definitely
some usability issues to be worked out. The Qt widget itself is
becoming fairly polished, but the application needs some work.

Evan