Re: I don't understand ncurses dealing with control-ARROW

[Steffen Nurpmeso]

Hello and good morning,

Thomas Dickey <address@hidden> wrote:
 |On Thu, Dec 17, 2015 at 10:52:38PM +0100, Steffen Nurpmeso wrote:

 |> I'm currently rewriting some code that deals with termcap (being
 |> out of the question before) and don't actually understand how to
 |> get at the control-ARROW etc. modifiers.

 |> nsterm, yet TERM=screen.xterm-256color (over ssh) and infocmp(1)
 |> doesn't output anything for kLFT5.  How do you do that?  ..Is this
 |> interpolated given that kLFT=\E[1;2D for both?  (..Likely..)
 |
 |no, it's not interpolated, but all explicit.  You have to add the "-x"
 |option of infocmp to see the extended/user-defined capabilities.

Oh.  Indeed, that shows them.  Fyi please note that i would not
have expected anything neither under user-defined nor under "treat
unknown as user-defined" (what tic says for -x).  I.e., isn't that
a regular entry?  And: which standard do i have to read to be able
to be enabled to tell so by myself?  (Maybe rethorical question :)

 |Comparing the output of these (nsterm with/without "-x"):
 ...

 |> My question is why this is kLFT5 given that Caps.keys says the
 |> capname will be kclft?  Also, for kclft there is a %k termcap
 |> mapping, but i couldn't find any hint on such a thing for kLFT5.
 |
 |oh... I'd have to say that Caps.keys was experimental
 | 
 |20010804                                                             \
 |           
 |        + add Caps.keys example for experimental extended function keys
 |   (adapted from a patch by Ilya Zakharevich).

Ah.

 |but that I did not take it into account when adding the xterm function
 |keys because (besides not thinking about it), there are many more
 |combinations of modifiers in xterm than the enumeration in Caps.keys
 |would handle.

Hm.  Then again not that much more (enough for __me__!!!!!).  But
of course you are right, you have to give a name to an entire
combination and that will lead you to nowhere.

 |Caps.keys is an example (like the other Caps.* files) which ncurses
 |could be compiled with, but I don't recall anyone actually using it.

Oh.  Well.  My way lead me over termcap(5) and terminfo(5) over
a remembered thread on the rxvt-unicode ML to several therein
referenced pages, one of which lead to the file Caps.keys, another
to your home page and the modifier table example for the delete
character function -- i think it was?  dc?  (Odysseus' was more
dangerous, but at least there were women along the way, hahaha..)

 |> For me the worst is that i cannot give end-users just any hint on
 |> how to get at the actual name nor sequence, except by copy+pasting
 |> a small C program that queries kLFT5++ and returns what is true as
 |> opposed to what infocmp says for $TERM.  I'm thinking about
 |> deliberately violating ncurses (?) by using tigetstr() in
 |> conjunction with tgetent() when it is available.
 |
 |I recommend using tigetstr, since tgetstr (termcap) won't handle the
 |longer names.

It would work.  Good to know.  I've added a note to the manual
that "$ cat" should be used and explained what escape is and how
to define a control character, and gave an example

  set termcap="%k=\033[D,%o=\033[C,%q=\033[A,%r=\033[B"

But if tigetstr() works even if i otherwise only use the old-style
termcap approach then i think i will extend the code again and use
it if available; since these are rather exotic functions the user
will have to manually adjust in other environments, which i hope
the manual will enable her to.

Thanks!  And ciao (and a merry Christmas, too),

--steffen