Third in a series (#1, #2) of questions occupying my mind at the beginning of 2014. Which may (or may not) inform what I’ll be working on.

3) How can we program on tablets?

I’m now a tablet user. I became a tablet owner at the end of 2012. For six months I played around with it, trying a few Android programming exercises. But I only really became a regular tablet user half-way through the year. Firstly when I put Mind Traffic Control into a responsive design. Secondly when I bought a couple of e-books. And I only really got committed when I did OWLdroid and coupled that with btsync.

So – somewhat late to the party, I admit – I’m now a tablet enthusiast.

And so my question is, how the hell do I program on this thing?

There’s a trivial answer to that question : get an external keyboard, an appropriate editor / IDE and treat it like a normal computer with a small screen. I can do that. I’ve worked a lot on netbooks and small screens don’t freak me out. But that’s not really what I mean.

Because tablets aren’t meant to have keyboards. And a computer without a keyboard challenges one of my deepest held programming beliefs : the superiority of plain text.

Plain-text is so flexible, so expressive, so powerful, so convenient to work with, that I’ve always been highly sceptical of those who want to do away with it. But on a keyboardless computer, it’s a different matter. Plain text isn’t at all convenient without a keyboard.

Especially the text of programming languages which makes rich use of another dozen or so punctuation symbols beyond the alphabet and numerals. And where manipulation relies on cursor-keys, shift and control, deletes (both forward and backspace), page up and down, tab-complete etc.

And yet tablets are becoming ubiquitous. Increasingly they’re the target of our programming, and the tool we have with us. So how are we going to program in this new environment? With multi-touch or stylus but no keyboard?

I have yet to see anything even vaguely plausible as the revolution in programming “language” we’re going to need for this.

I don’t think it’s the “Scratch”-like or “App Inventor”-like “stick the blocks together” languages. The problem of programming on tablets shouldn’t be conflated with the problem of teaching novices to program. (Which is what most visual programming environments seem to be about.)

One issue with that kind of system (and other “flow-charts”) is that blocks need to be big enough to be easily and unambiguously manipulated with fat fingers. But to be decently usable, a programming system should be able to have a reasonable density of information on the screen, otherwise you’ll spend all your time scrolling and forgetting what you’ve seen. How do you resolve that tension?

Perhaps “data-flow” programming of the Max/MSP, PD, Quartz kind. Piping diagrams. Process Modelling packages have something to teach us about orchestrating in the large. But they are shockingly clumsy for certain fine-grained activities that are expressed easily in text. (Eg. how the hell can you talk about tree-shaped data or recursive algorithms using this kind of piping model?)

So I don’t have any information about who is doing interesting work in this area. (Aside : while writing this post, I thought I’d consult the collective wisdom on StackExchange. Needless to say, my question was immediately shot down as too vague.) But I’m now very curious about it.

I’ve been travelling with my trusty (but ageing) eeepc netbook this last week. There’s much to love about it but it’s starting to feel slow in comparison with my other machine.

Increasingly when I use the netbook I try to get away with doing things in a ctrl-alt-f1 shell without logging in to the GUI at all. I’m starting to wish more software could be used in this environment so I began to look at Curses, the standard library for text-window UIs. There’s a convenient Python wrapper of course. And there’s another nice library in Python : Cmd, for creating a command-line driven apps. That is, not programs that literally run as small tools on the shell with command-line arguments, but programs which have their own internal “repl” style loop which you drive by typing in commands. Cmd handily hides the details from you, letting you declare a subclass of the Cmd class which simply defines handlers for specific commands. It’s not a million miles away from something I ended up writing to handle the commands in SdiDesk.

For some of my projects it would be useful to combine the two modes : to have Cmd style input driving a 2D textual output using Curses. Unfortunately Cmd and Curses don’t obviously play well together.  Both of them want to take over the input, with Curses thinking in terms of keystrokes while Cmd still expects full lines.

Nevertheless, after a bit of exploration, and learning about Curses’s textpads and Cmd’s supplementary methods, I’m starting to get the two to co-operate. As this gist shows :

It doesn’t do anything yet. Just handles a “greet NAME” command that prints “hello NAME”. And a “quit” command that exits the program. But it has combined Cmd inputs with Curses output.