php-doc-en/reference/readline/functions/readline-callback-handler-install.xml

<?xml version="1.0" encoding="utf-8"?>
<!-- $Revision$ -->
<refentry xml:id="function.readline-callback-handler-install" xmlns="http://docbook.org/ns/docbook">
 <refnamediv>
  <refname>readline_callback_handler_install</refname>
  <refpurpose>Initializes the readline callback interface and terminal, prints the prompt and returns immediately</refpurpose>
 </refnamediv>
 
 <refsect1 role="description">
  &reftitle.description;
  <methodsynopsis>
   <type>bool</type><methodname>readline_callback_handler_install</methodname>
   <methodparam><type>string</type><parameter>prompt</parameter></methodparam>
   <methodparam><type>callable</type><parameter>callback</parameter></methodparam>
  </methodsynopsis>
  <para>
   Sets up a readline callback interface then prints
   <parameter>prompt</parameter> and immediately returns.  
   Calling this function twice without removing the previous
   callback interface will automatically and conveniently overwrite the old
   interface.
  </para>
  <para>
   The callback feature is useful when combined with
   <function>stream_select</function> as it allows interleaving of IO and
   user input, unlike <function>readline</function>.
  </para>
 </refsect1>

 <refsect1 role="parameters">
  &reftitle.parameters;
  <para>
   <variablelist>
    <varlistentry>
     <term><parameter>prompt</parameter></term>
     <listitem>
      <para>
       The prompt message.
      </para>
     </listitem>
    </varlistentry>
    <varlistentry>
     <term><parameter>callback</parameter></term>
     <listitem>
      <para>
       The <parameter>callback</parameter> function takes one parameter; the
       user input returned.
      </para>
     </listitem>
    </varlistentry>
   </variablelist>
  </para>
 </refsect1>

 <refsect1 role="returnvalues">
  &reftitle.returnvalues;
  <para>
   &return.success;
  </para>
 </refsect1>
 
 <refsect1 role="examples">
  &reftitle.examples;
  <para>
   <example>
    <title>Readline Callback Interface Example</title>
    <programlisting role="php">
<![CDATA[
<?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";
?>
]]>
    </programlisting>
   </example>
  </para>
 </refsect1>

 <refsect1 role="seealso">
  &reftitle.seealso;
  <para>
   <simplelist>
    <member><function>readline_callback_handler_remove</function></member>
    <member><function>readline_callback_read_char</function></member>
    <member><function>stream_select</function></member>
   </simplelist>
  </para>
 </refsect1>

</refentry>

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