Here is what I am talking about:
Is it possible to implement? (unless it’s already present)
From this video, all you need to do is select the two edges and press the F key, which fills in a face between two, three, or four edges. I don’t believe there are any methods simpler than this, if that is what you are asking, but I definitely could be wrong. Some other answers might clear up your question more. If I completely took your question the wrong way, just tell me ;).
Thanks,
Geo
Lol, you actually look at it wrong way 
I have to fill out two faces. As you can see on the video, that’s what I am doing first time around - select 2 edges, F, select another 2 edges, F.
Second time around I select all 4 edges, and press F. So with smart fill, left side would fill and right side would fill.
Now imagine that instead of 2 faces, I need to fill 10 faces. So instead of selecting pair of edges 10 times, I would only need to select it once, press F once and get them filled properly.
well if you have a model that is symetrical, use mirror modifier 
The point is you have define what is smart filling, and make sure it could be formulated in a logical way so it can be coded.
How to discriminate between edges that should be connected ?.
if its based on selection order then it might be done in python, but that might be a lot work if your not into python, try the scripting forum.
That makes much more sense :yes: I don’t believe there is any built-in feature for this as bridge edge loops wouldn’t cut it in that specific situation (though it would work in some like that). I am trying to think how this would be accomplished as I think it might be hard to determine which way to join the faces - in your case along the x or y axes. This would be a great script, filling in between the shortest distance possibly. This might work in the cases where bridge edge loops wouldn’t. Hopefully we can get some more insight on this as I think it could help many blender users.
Thanks,
Geo
It’s not a rocket science to understand what’s “smart fill” would be by watching videos and paying attention to what’s being done 
Select all open “holes” one the mesh, press F once and they all get filled nicely as if you were doing it “hole” by “hole”.
Or better yet, have a tool to select holes (edges or vertices) and fill them. This would save even more time.
After reading that thread i was about to post that this kind of “smart fill” is already a feature, but after a quick check to see if i had not imagined things when modelling, i saw where it fail : it seems to work only in vertices selection mode.
I mean, if i select those edges in edge selection mode :
And press F, it will be only very ugly, there’s no smart filling, it get actually very bad.
Now if from the screenshot, instead of pressing F , i switch to vertices selection mode :
Then i press F , and it’s smartly filled there :
So it looks like you can select edges like you did in the video, but from there you must switch to vertices select mode before pressing F
edit : oh just noticed i missed a post in which it’s been said already
Thanks Sanctuary!
Select non-manifold, then F does the job well!
Menu>Mesh>Clean up> Fill Holes
Hi try
select all / select link > select boundary loop > face
i forgot where i get the command
to try => input editor => mesh mode > mesh.region_to_loop