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<title>Initializes the readline callback interface and terminal, prints the prompt and returns immediately</title>
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<h1 class="refname">readline_callback_handler_install</h1>
<p class="verinfo">(PHP 5 >= 5.1.0)</p><p class="refpurpose"><span class="refname">readline_callback_handler_install</span> — <span class="dc-title">Initializes the readline callback interface and terminal, prints the prompt and returns immediately</span></p>
</div>
<div class="refsect1 description" id="refsect1-function.readline-callback-handler-install-description">
<h3 class="title">Description</h3>
<div class="methodsynopsis dc-description">
<span class="type">bool</span> <span class="methodname"><strong>readline_callback_handler_install</strong></span>
( <span class="methodparam"><span class="type">string</span> <code class="parameter">$prompt</code></span>
, <span class="methodparam"><span class="type"><a href="language.types.callable.html" class="type callable">callable</a></span> <code class="parameter">$callback</code></span>
)</div>
<p class="para rdfs-comment">
Sets up a readline callback interface then prints
<em><code class="parameter">prompt</code></em> and immediately returns.
Calling this function twice without removing the previous
callback interface will automatically and conveniently overwrite the old
interface.
</p>
<p class="para">
The callback feature is useful when combined with
<span class="function"><a href="function.stream-select.html" class="function">stream_select()</a></span> as it allows interleaving of IO and
user input, unlike <span class="function"><a href="function.readline.html" class="function">readline()</a></span>.
</p>
</div>
<div class="refsect1 parameters" id="refsect1-function.readline-callback-handler-install-parameters">
<h3 class="title">Parameters</h3>
<p class="para">
<dl>
<dt>
<span class="term"><em><code class="parameter">prompt</code></em></span>
<dd>
<p class="para">
The prompt message.
</p>
</dd>
</dt>
<dt>
<span class="term"><em><code class="parameter">callback</code></em></span>
<dd>
<p class="para">
The <em><code class="parameter">callback</code></em> function takes one parameter; the
user input returned.
</p>
</dd>
</dt>
</dl>
</p>
</div>
<div class="refsect1 returnvalues" id="refsect1-function.readline-callback-handler-install-returnvalues">
<h3 class="title">Return Values</h3>
<p class="para">
Returns <strong><code>TRUE</code></strong> on success or <strong><code>FALSE</code></strong> on failure.
</p>
</div>
<div class="refsect1 description" id="refsect1-function.readline-callback-handler-install-description">
<h3 class="title">Examples</h3>
<p class="para">
<div class="example" id="example-642">
<p><strong>Example #1 Readline Callback Interface Example</strong></p>
<div class="example-contents">
<div class="phpcode"><code><span style="color: #000000">
<span style="color: #0000BB"><?php<br /></span><span style="color: #007700">function </span><span style="color: #0000BB">rl_callback</span><span style="color: #007700">(</span><span style="color: #0000BB">$ret</span><span style="color: #007700">)<br />{<br /> global </span><span style="color: #0000BB">$c</span><span style="color: #007700">, </span><span style="color: #0000BB">$prompting</span><span style="color: #007700">;<br /><br /> echo </span><span style="color: #DD0000">"You entered: </span><span style="color: #0000BB">$ret</span><span style="color: #DD0000">\n"</span><span style="color: #007700">;<br /> </span><span style="color: #0000BB">$c</span><span style="color: #007700">++;<br /><br /> if (</span><span style="color: #0000BB">$c </span><span style="color: #007700">> </span><span style="color: #0000BB">10</span><span style="color: #007700">) {<br /> </span><span style="color: #0000BB">$prompting </span><span style="color: #007700">= </span><span style="color: #0000BB">false</span><span style="color: #007700">;<br /> </span><span style="color: #0000BB">readline_callback_handler_remove</span><span style="color: #007700">();<br /> } else {<br /> </span><span style="color: #0000BB">readline_callback_handler_install</span><span style="color: #007700">(</span><span style="color: #DD0000">"[</span><span style="color: #0000BB">$c</span><span style="color: #DD0000">] Enter something: "</span><span style="color: #007700">, </span><span style="color: #DD0000">'rl_callback'</span><span style="color: #007700">);<br /> }<br />}<br /><br /></span><span style="color: #0000BB">$c </span><span style="color: #007700">= </span><span style="color: #0000BB">1</span><span style="color: #007700">;<br /></span><span style="color: #0000BB">$prompting </span><span style="color: #007700">= </span><span style="color: #0000BB">true</span><span style="color: #007700">;<br /><br /></span><span style="color: #0000BB">readline_callback_handler_install</span><span style="color: #007700">(</span><span style="color: #DD0000">"[</span><span style="color: #0000BB">$c</span><span style="color: #DD0000">] Enter something: "</span><span style="color: #007700">, </span><span style="color: #DD0000">'rl_callback'</span><span style="color: #007700">);<br /><br />while (</span><span style="color: #0000BB">$prompting</span><span style="color: #007700">) {<br /> </span><span style="color: #0000BB">$w </span><span style="color: #007700">= </span><span style="color: #0000BB">NULL</span><span style="color: #007700">;<br /> </span><span style="color: #0000BB">$e </span><span style="color: #007700">= </span><span style="color: #0000BB">NULL</span><span style="color: #007700">;<br /> </span><span style="color: #0000BB">$n </span><span style="color: #007700">= </span><span style="color: #0000BB">stream_select</span><span style="color: #007700">(</span><span style="color: #0000BB">$r </span><span style="color: #007700">= array(</span><span style="color: #0000BB">STDIN</span><span style="color: #007700">), </span><span style="color: #0000BB">$w</span><span style="color: #007700">, </span><span style="color: #0000BB">$e</span><span style="color: #007700">, </span><span style="color: #0000BB">null</span><span style="color: #007700">);<br /> if (</span><span style="color: #0000BB">$n </span><span style="color: #007700">&& </span><span style="color: #0000BB">in_array</span><span style="color: #007700">(</span><span style="color: #0000BB">STDIN</span><span style="color: #007700">, </span><span style="color: #0000BB">$r</span><span style="color: #007700">)) {<br /> </span><span style="color: #FF8000">// read a character, will call the callback when a newline is entered<br /> </span><span style="color: #0000BB">readline_callback_read_char</span><span style="color: #007700">();<br /> }<br />}<br /><br />echo </span><span style="color: #DD0000">"Prompting disabled. All done.\n"</span><span style="color: #007700">;<br /></span><span style="color: #0000BB">?></span>
</span>
</code></div>
</div>
</div>
</p>
</div>
<div class="refsect1 seealso" id="refsect1-function.readline-callback-handler-install-seealso">
<h3 class="title">See Also</h3>
<p class="para">
<ul class="simplelist">
<li class="member"> <span class="function"><a href="function.readline-callback-handler-remove.html" class="function" rel="rdfs-seeAlso">readline_callback_handler_remove()</a> - Removes a previously installed callback handler and restores terminal settings</span></li>
<li class="member"> <span class="function"><a href="function.readline-callback-read-char.html" class="function" rel="rdfs-seeAlso">readline_callback_read_char()</a> - Reads a character and informs the readline callback interface when a line is received</span></li>
<li class="member"> <span class="function"><a href="function.stream-select.html" class="function" rel="rdfs-seeAlso">stream_select()</a> - Runs the equivalent of the select() system call on the given
arrays of streams with a timeout specified by tv_sec and tv_usec</span></li>
</ul>
</p>
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