pyNCS headless

[eneftci]

I noticed that pyNCS does not load if no display is available. This is annoying if one wants to run through ssh in combination with nohup (I use this for starting a long experiment through ssh and leave at night). This can also be a problem for Mac users connecting to a server through ssh and that have no local X server.

The cause is traitsui.api in ConfAPI.py . The parameter object inherits from hastraits. There seems to be no easy way to cut its dependency to display. Enthought is certainly a nice tool in some cases, but documentation is awful for a package of its size and importance. So I am wondering whether we should get rid of any enthought calls in the core part of pyNCS (i.e. whatever is imported in init).

A workaround for the display problem is to use a virtual frame buffer:
xvfb-run --server-args="-screen 0 1024x768x24" python my_pyncs_script.py

[sheiksadique]

Yes I noticed that too.. Here is something i was considering doing

1. Removing enthouht dependency entirely. That would be a pity because it would have been awesome for developing GUIs for demos.

2. developing a fake enthought/chaco package so that those will be imported when the actual cannot be imported due to any reason at all.

3. May be we should consider developing a sub package pyNCS.ui which will support GUI stuff and will ofcourse only work when possible. I dont have a clue at this moment how this will work. This would be in the direction you were suggesting.

Which do you prefer ? And how urgent is this issue ? Option 1 would be the quickest and 3 the slowest.

[eneftci]

Actually 3) is pretty good.

For example, you could have Parameter inherit from a HasTraitsAble (virtual) class that would have the functions necessary to cast it into a HasTraits. It is not urgent since there is a work around for this problem using the virtual framebuffer (xvfb).

[fabioedoardoluigialberto]

I also favour the 3rd option. Maybe it is going to be easy to implement with the guiqwt thing.

[sheiksadique]

New branch "headless" added.
Unit test runs without errors.
Can you guys beta test ? Thanks.