GNU Readline Library
2.4.12 Alternate Interface
An alternate interface is available to plain readline(). Some
applications need to interleave keyboard I/O with file, device, or
window system I/O, typically by using a main loop to select()
on various file descriptors. To accomodate this need, readline can
also be invoked as a `callback' function from an event loop. There
are functions available to make this easy.
- Function: void rl_callback_handler_install (const char *prompt, rl_vcpfunc_t *lhandler)
- Set up the terminal for readline I/O and display the initial
expanded value of prompt. Save the value of lhandler to
use as a function to call when a complete line of input has been entered.
The function takes the text of the line as an argument.
- Function: void rl_callback_read_char (void)
- Whenever an application determines that keyboard input is available, it
should call
rl_callback_read_char(), which will read the next
character from the current input source.
If that character completes the line, rl_callback_read_char will
invoke the lhandler function saved by rl_callback_handler_install
to process the line.
Before calling the lhandler function, the terminal settings are
reset to the values they had before calling
rl_callback_handler_install.
If the lhandler function returns,
the terminal settings are modified for Readline's use again.
EOF is indicated by calling lhandler with a
NULL line.
- Function: void rl_callback_handler_remove (void)
- Restore the terminal to its initial state and remove the line handler.
This may be called from within a callback as well as independently.
If the lhandler installed by
rl_callback_handler_install
does not exit the program, either this function or the function referred
to by the value of rl_deprep_term_function should be called before
the program exits to reset the terminal settings.
