File operations now always return a channel (or nil on error or
permission denied).
When start_reading() from a filename, you can repeatedly :recv() from
the channel it returns.
When :recv() returns nil, you're at the end of the file. Stop.
When you start_writing() to a filename, you can repeatedly :send() to
the channel it returns.
When you're done writing, :close() the channel. Writes to the file won't
be externally visible until you do.
To make this work I'm now always starting up the scheduler, so I need to
fix sieve.tlv.
Transparently running the scheduler is an abstraction, and whenever I
create an abstraction I always worry about how it might fail. There's
a hopefully-clear error when you read past end of a file.
Tasteful apps should only perform side-effects through 'window'
arguments rather than the 'curses' module directly. It's ok however to
read constants like curses.A_NORMAL or curses.stdscr().
There are some limitations, unfortunately. Ncurses wasn't designed with
testability in mind. For example, there's no way to curs_set or
assume_default_colors without the 'curses' module. Oh well.
Kartik K. Agaram