todo

操作系统SunOS 4.1.3版本的源码

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# @(#)TODO 1.1 92/07/30 SMI; from S5R3 1.2.1.1
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This file documents things I would like to see done to curses
that I simply don't have time for.  I can design them but there
is no time to implement them.  Someone should.

HP terminals: performance on HP terminals is terrible, because it
outputs ESC & d x before every character that has the highlighting
changed.  I was unable to make it work without doing this.  To make
it work, you're going to have to keep a data structure of cookies
that are on the screen, and when one gets in the way, change it.
This is hard because operations like ins/del line, ins/del char,
ceol, and clear affect the cookie map.  The philosophy has to change,
currently it's "output cookies everywhere", it should change to
"output as few cookies as you can get away with".

Lots of variations.  The Ann Arbor Guru (and to a lesser extent the
Ambassador) point out an amazing number of modes you might want to
run the terminal in.  Different sizes, different amounts of memory,
normal or reverse video, with or without a status line, with or without
context, with or without destructive backspace, etc.  Including entries
for all these possibilities is not only a lot of work (even with use=
you have to list them all) but each one takes up lots of space.  Adding
a new option with two possibilities doubles the number of terminal types
(and hence the amount of disk spaced needed for the binaries).

The solution to this is to make setupterm smarter about how it looks
up terminal type names.  It should start with $TERM.  If that isn't
there, it should strip off the final -opt and try that.  Keep stripping
off -opt's until you find one.  Then look for "delta files" showing
how to change the default for these options.  For example
	aaa-60-s-rv
Assume there is no aaa-60-s-rv.  Try aaa-60-s.  That fails, so try
aaa-60.  Suppose that works.  You read in aaa-60, then search for
aaa+s (the + is used internally to indicate an option, see the source
code to terminfo for examples.)  The contents of aaa+s is applied as
a difference to aaa-60.  Then aaa+rv is looked up, and it is applied
as a delta.  This will require a new value in a compiled terminfo file:
"unknown", plus "cancel".  If you interpret the current missing values
(0 for Bool, -1 for int, 0 for string) as "unknown" in a delta (rather
than "not present") you'll just need one new value - "cancel", which
could be -1 for bool, -2 for int, -1 for string.  -2 should be defined
as 377, 376.

By convention, -60 means "60 lines", -x80 means "by 80", that is, "80
columns", and -60x80 means "60 lines, 80 cols".  These should override
the default "lines" and "columns", although this is a last resort, and
you should check for the appropriate file first (there might be some
other changes to some init strings, for example.)

It would be nice to be able to define capabilities as strings and include
them in the middle of other capabilities.  For instance:
	foo,
		is2=\E[^(lines);^(columns)z,
might mean that the values of "lines" and "columns" (taken as text)
should be inserted at these two points, to initialize the screen size.
The ^(cap) notation won't conflict with existing usage.  The interpretation
must be done by setupterm, since at compile time you don't know what
the capabilities values are.  Some clever storage scheme will be needed
since the compiler interprets existing ^'s, e.g. use the parity bit.

Some future code changes and optimizations:

	Get rid of _lastch since the information is never used
	In _init_costs, add some decisions about using ins/del line
		vs. scrolling regions so that it doesn't have to
		be constantly checked
	Rewrite _showstring()