php-doc-en/reference/ev/evchild/construct.xml

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<refentry xml:id="evchild.construct" xmlns="http://docbook.org/ns/docbook" xmlns:xlink="http://www.w3.org/1999/xlink">
 <refnamediv>
  <refname>EvChild::__construct</refname>
  <refpurpose>Constructs the EvChild watcher object</refpurpose>
 </refnamediv>

 <refsect1 role="description">
  &reftitle.description;
  <methodsynopsis>
   <modifier>public</modifier> <methodname>EvChild::__construct</methodname>
   <methodparam><type>int</type><parameter>pid</parameter></methodparam>
   <methodparam><type>bool</type><parameter>trace</parameter></methodparam>
   <methodparam><type>callable</type><parameter>callback</parameter></methodparam>
   <methodparam
   choice="opt"><type>mixed</type><parameter>data</parameter><initializer>&null;</initializer></methodparam>
   <methodparam
   choice="opt"><type>int</type><parameter>priority</parameter><initializer>0</initializer></methodparam>
  </methodsynopsis>
  <para>
  Constructs the <classname>EvChild</classname> watcher object.
  </para>
  <para>
    Call the callback when a status change for process ID
    <parameter>pid</parameter>(or any <emphasis>PID</emphasis> if
    <parameter>pid</parameter> is <constant>0</constant>) has been received(a
    status change happens when the process terminates or is killed, or, when
    <parameter>trace</parameter> is &true;, additionally when it is stopped or
    continued). In other words, when the process receives a
    <constant>SIGCHLD</constant>, <emphasis>Ev</emphasis> will fetch the
    outstanding exit/wait status for all changed/zombie children and call the
    callback.
  </para>
  <para>
    It is valid to install a child watcher after an
    <classname>EvChild</classname> has exited but before the event loop has
    started its next iteration(for example, first you fork, then the new child
    process might exit, and only then do you install an
    <classname>EvChild</classname> watcher in the parent for the new
    <emphasis>PID</emphasis>).
  </para>
  <para>
    You can access both exit/tracing status and <parameter>pid</parameter> by
    using the <varname>rstatus</varname> and <varname>rpid</varname>
    properties of the watcher object.
  </para>
  <para>
    You can have as many <emphasis>PID</emphasis> watchers per
    <emphasis>PID</emphasis> as you want, they will all be called.
  </para>
  <para>
    The <methodname>EvChild::createStopped</methodname> method doesn't
    start(activate) the newly created watcher.
  </para>

 </refsect1>

 <refsect1 role="parameters">
  &reftitle.parameters;
  <variablelist>
   <varlistentry>
    <term><parameter>pid</parameter></term>
    <listitem>
     <para>
     Wait for status changes of process PID(or any process if PID is specified
     as <constant>0</constant>).
     </para>
    </listitem>
   </varlistentry>
   <varlistentry>
    <term><parameter>trace</parameter></term>
    <listitem>
     <para>
      If &false;, only activate the watcher when the process terminates.
      Otherwise(&true;) additionally activate the watcher when the process is
      stopped or continued.
     </para>
    </listitem>
   </varlistentry>
   <varlistentry>
    <term><parameter>callback</parameter></term>
    <listitem>
     <para>
     See <link linkend="ev.watcher-callbacks">Watcher callbacks</link>.
     </para>
    </listitem>
   </varlistentry>
   <varlistentry>
    <term><parameter>data</parameter></term>
    <listitem>
     <para>
      Custom data associated with the watcher.
     </para>
    </listitem>
   </varlistentry>
   <varlistentry>
    <term><parameter>priority</parameter></term>
    <listitem>
     <para>
      <link linkend="ev.constants.watcher-pri">Watcher priority</link>
     </para>
    </listitem>
   </varlistentry>
  </variablelist>
 </refsect1>

 <refsect1 role="returnvalues">
  &reftitle.returnvalues;
  <para>
  Returns EvChild object on success.
  </para>
 </refsect1>

 <refsect1 role="seealso">
  &reftitle.seealso;
  <simplelist>
   <member><methodname>EvLoop::child</methodname></member>
  </simplelist>
 </refsect1>

</refentry>

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