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# readline_callback_handler_install

(PHP 5)

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

## 说明

bool readline_callback_handler_install ( string prompt, callback callback )

Sets up a readline callback interface then prints prompt and immediately returns. The callback function takes one parameter; the user input returned. 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().

## 返回值

如果成功则返回 `TRUE`，失败则返回 `FALSE`。

## 例

例子 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) {
$n = stream_select($r = array(STDIN), $w = null, $e = null, null);
if ($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";
?>`

## 参见

readline_callback_handler_remove(), readline_callback_read_char() 和 stream_select().

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