Readline Functions
PHP Manual

readline_callback_handler_install

Initializes the readline callback interface and terminal, prints the prompt and returns immediately

Description

true readline_callback_handler_install(string $prompt, callable $callback)

Sets up a readline callback interface then prints prompt and immediately returns. Calling this function twice without removing the previous callback interface will automatically and conveniently overwrite the old interface.

The callback feature is useful when combined with stream_select as it allows interleaving of IO and user input, unlike readline.

Parameters

prompt

The prompt message.

callback

The callback function takes one parameter; the user input returned.

Return Values

Always returns true.

Examples

Example #1 Readline Callback Interface Example

<?php
function rl_callback($ret)
{
    global $c, $prompting;

    echo "You entered: $ret\n";
    $c++;

    if ($c > 10) {
        $prompting = false;
        readline_callback_handler_remove();
    } else {
        readline_callback_handler_install("[$c] Enter something: ", 'rl_callback');
    }
}

$c = 1;
$prompting = true;

readline_callback_handler_install("[$c] Enter something: ", 'rl_callback');

while ($prompting) {
    $w = NULL;
    $e = NULL;
    $n = stream_select($r = array(STDIN), $w, $e, null);
    if ($n && in_array(STDIN, $r)) {
        // read a character, will call the callback when a newline is entered
        readline_callback_read_char();
    }
}

echo "Prompting disabled. All done.\n";
?>

See Also

  • readline_callback_handler_remove
  • readline_callback_read_char
  • stream_select