path: root/docs/reference/pygio-inputstream.xml

<?xml version="1.0" standalone="no"?>
<!DOCTYPE refentry PUBLIC "-//OASIS//DTD DocBook XML V4.1.2//EN"
    "http://www.oasis-open.org/docbook/xml/4.1.2/docbookx.dtd">

<refentry id="class-gioinputstream">
    <refnamediv>
        <refname>gio.InputStream</refname>
        <refpurpose>Base class for implementing streaming input</refpurpose>
    </refnamediv>

    <refsect1>
        <title>Synopsis</title>

    <classsynopsis language="python">
        <ooclass><classname>gio.InputStream</classname></ooclass>
        <ooclass><classname><link linkend="class-gobject">gobject.GObject</link></classname></ooclass>

    <methodsynopsis language="python">
        <methodname><link linkend="method-gioinputstream--clear-pending">clear_pending</link></methodname>
        <methodparam></methodparam>
    </methodsynopsis>
    <methodsynopsis language="python">
        <methodname><link linkend="method-gioinputstream--close">close</link></methodname>
        <methodparam><parameter role="keyword">cancellable</parameter><initializer>None</initializer></methodparam>
    </methodsynopsis>
    <methodsynopsis language="python">
        <methodname><link linkend="method-gioinputstream--close-async">close_async</link></methodname>
        <methodparam><parameter role="keyword">callback</parameter></methodparam>
        <methodparam><parameter role="keyword">io_priority</parameter><initializer>glib.PRIORITY_DEFAULT</initializer></methodparam>
        <methodparam><parameter role="keyword">cancellable</parameter><initializer>None</initializer></methodparam>
        <methodparam><parameter role="keyword">user_data</parameter><initializer>None</initializer></methodparam>
    </methodsynopsis>
    <methodsynopsis language="python">
        <methodname><link linkend="method-gioinputstream--close-finish">close_finish</link></methodname>
        <methodparam><parameter role="keyword">result</parameter></methodparam>
    </methodsynopsis>
    <methodsynopsis language="python">
        <methodname><link linkend="method-gioinputstream--has-pending">has_pending</link></methodname>
        <methodparam></methodparam>
    </methodsynopsis>
    <methodsynopsis language="python">
        <methodname><link linkend="method-gioinputstream--is-closed">is_closed</link></methodname>
        <methodparam></methodparam>
    </methodsynopsis>
    <methodsynopsis language="python">
        <methodname><link linkend="method-gioinputstream--read">read</link></methodname>
        <methodparam><parameter role="keyword">count</parameter><initializer>-1</initializer></methodparam>
        <methodparam><parameter role="keyword">cancellable</parameter><initializer>None</initializer></methodparam>
    </methodsynopsis>
    <methodsynopsis language="python">
        <methodname><link linkend="method-gioinputstream--read-async">read_async</link></methodname>
        <methodparam><parameter role="keyword">count</parameter></methodparam>
        <methodparam><parameter role="keyword">callback</parameter></methodparam>
        <methodparam><parameter role="keyword">io_priority</parameter><initializer>glib.PRIORITY_DEFAULT</initializer></methodparam>
        <methodparam><parameter role="keyword">cancellable</parameter><initializer>None</initializer></methodparam>
        <methodparam><parameter role="keyword">user_data</parameter><initializer>None</initializer></methodparam>
    </methodsynopsis>
    <methodsynopsis language="python">
        <methodname><link linkend="method-gioinputstream--read-finish">read_finish</link></methodname>
        <methodparam><parameter role="keyword">result</parameter></methodparam>
    </methodsynopsis>
    <methodsynopsis language="python">
        <methodname><link linkend="method-gioinputstream--read-part">read_part</link></methodname>
        <methodparam><parameter role="keyword">count</parameter><initializer>-1</initializer></methodparam>
        <methodparam><parameter role="keyword">cancellable</parameter><initializer>None</initializer></methodparam>
    </methodsynopsis>
    <methodsynopsis language="python">
        <methodname><link linkend="method-gioinputstream--set-pending">set_pending</link></methodname>
        <methodparam></methodparam>
    </methodsynopsis>
    <methodsynopsis language="python">
        <methodname><link linkend="method-gioinputstream--skip">skip</link></methodname>
        <methodparam><parameter role="keyword">count</parameter></methodparam>
        <methodparam><parameter role="keyword">cancellable</parameter><initializer>None</initializer></methodparam>
    </methodsynopsis>
    <methodsynopsis language="python">
        <methodname><link linkend="method-gioinputstream--skip-async">skip_async</link></methodname>
        <methodparam><parameter role="keyword">count</parameter></methodparam>
        <methodparam><parameter role="keyword">callback</parameter></methodparam>
        <methodparam><parameter role="keyword">io_priority</parameter><initializer>glib.PRIORITY_DEFAULT</initializer></methodparam>
        <methodparam><parameter role="keyword">cancellable</parameter><initializer>None</initializer></methodparam>
        <methodparam><parameter role="keyword">user_data</parameter><initializer>None</initializer></methodparam>
    </methodsynopsis>
    <methodsynopsis language="python">
        <methodname><link linkend="method-gioinputstream--skip-finish">skip_finish</link></methodname>
        <methodparam><parameter role="keyword">result</parameter></methodparam>
    </methodsynopsis>

    </classsynopsis>

    </refsect1>

    <refsect1>
        <title>Ancestry</title>

<synopsis>+-- <link linkend="class-gobject">gobject.GObject</link>
  +-- <link linkend="class-gioinputstream">gio.InputStream</link>
</synopsis>

    </refsect1>

    <refsect1>
        <title>Description</title>

        <para>
            <link linkend="class-gioinputstream"><classname>gio.InputStream</classname></link>
            has functions to read from a stream (
            <methodname><link linkend="method-gioinputstream--read">gio.InputStream.read</link></methodname>()
            ), to close a stream (
            <methodname><link linkend="method-gioinputstream--close">gio.InputStream.close</link></methodname>()
            ) and to skip some content (
            <methodname><link linkend="method-gioinputstream--skip">gio.InputStream.skip</link></methodname>()
            ).
        </para>
        <para>
            To copy the content of an input stream to an output stream without manually
            handling the reads and writes, use
            <methodname><link linkend="method-giooutputstream--skip">gio.OutputStream.splice</link></methodname>().
        </para>
        <para>
            All of these functions have async variants too.
        </para>
    </refsect1>

    <refsect1>
        <title>Methods</title>

        <refsect2 id="method-gioinputstream--clear-pending">
            <title>gio.InputStream.clear_pending</title>

            <programlisting><methodsynopsis language="python">
                <methodname>clear_pending</methodname>
                <methodparam></methodparam>
            </methodsynopsis></programlisting>
            
            <variablelist>
            </variablelist>
    
            <para>
                The <methodname>clear_pending</methodname>() method clears the pending flag on stream.
            </para>
        </refsect2>

        <refsect2 id="method-gioinputstream--close">
            <title>gio.InputStream.close</title>

            <programlisting><methodsynopsis language="python">
                <methodname>close</methodname>
                <methodparam><parameter role="keyword">cancellable</parameter><initializer>None</initializer></methodparam>
            </methodsynopsis></programlisting>
            
            <variablelist>
                <varlistentry>
                  <term><parameter role="keyword">cancellable</parameter>&nbsp;:</term>
                  <listitem><simpara>optional
                    <link linkend="class-giocancellable"><classname>gio.Cancellable</classname></link>
                    object, <literal>None</literal> to ignore.
                  </simpara></listitem>
                </varlistentry>
                <varlistentry>
                    <term><emphasis>Returns</emphasis>&nbsp;:</term>
                    <listitem><simpara><literal>True</literal> on success
                    <literal>False</literal> on failure.
                    </simpara></listitem>
                </varlistentry>
            </variablelist>
    
            <para>
                The <methodname>close</methodname>() method closes the stream, releasing
                resources related to it.
            </para>
            <para>
                Once the stream is closed, all other operations will return gio.IO_ERROR_CLOSED.
                Closing a stream multiple times will not return an error.
            </para>
            <para>
                Streams will be automatically closed when the last reference is dropped, but
                you might want to call this function to make sure resources are released as
                early as possible.
            </para>
            <para>
                Some streams might keep the backing store of the stream (e.g. a file descriptor)
                open after the stream is closed. See the documentation for the individual
                stream for details.
            </para>
            <para>
                On failure the first error that happened will be reported, but the close operation
                will finish as much as possible. A stream that failed to close will still return
                gio.IO_ERROR_CLOSED for all operations. Still, it is important to check and report
                the error to the user.
            </para>
            <para>
                If cancellable is not <literal>None</literal>, then the operation can be cancelled by
                triggering the cancellable object from another thread. If the operation was cancelled,
                the error gio.IO_ERROR_CANCELLED will be returned. Cancelling a close will still leave
                the stream closed, but some streams can use a faster close that doesn't block to e.g.
                check errors.
            </para>
        </refsect2>

        <refsect2 id="method-gioinputstream--close-async">
            <title>gio.InputStream.close_async</title>

            <programlisting><methodsynopsis language="python">
                <methodname>close_async</methodname>
                <methodparam><parameter role="keyword">callback</parameter></methodparam>
                <methodparam><parameter role="keyword">io_priority</parameter><initializer>glib.PRIORITY_DEFAULT</initializer></methodparam>
                <methodparam><parameter role="keyword">cancellable</parameter><initializer>None</initializer></methodparam>
                <methodparam><parameter role="keyword">user_data</parameter><initializer>None</initializer></methodparam>
            </methodsynopsis></programlisting>
            
            <variablelist>
                <varlistentry>
                    <term><parameter>callback</parameter>&nbsp;:</term>
                    <listitem><simpara>a GAsyncReadyCallback to call when the request is satisfied.
                    </simpara></listitem>
                </varlistentry>
                <varlistentry>
                    <term><parameter>io_priority</parameter>&nbsp;:</term>
                    <listitem><simpara>the
                    <xref linkend="glib-priority-constants" endterm="glib-priority-constants-title"></xref>
                    of the request. 
                    </simpara></listitem>
                </varlistentry>
                <varlistentry>
                    <term><parameter>cancellable</parameter>&nbsp;:</term>
                    <listitem><simpara>optional
                    <link linkend="class-giocancellable"><classname>gio.Cancellable</classname></link>
                    object, <literal>None</literal> to ignore.</simpara></listitem>
                </varlistentry>
                <varlistentry>
                    <term><parameter>user_data</parameter>&nbsp;:</term>
                    <listitem><simpara>the data to pass to callback function.
                    </simpara></listitem>
                </varlistentry>
            </variablelist>
    
            <para>
                The <methodname>close_async</methodname>() method asynchronously requests an
                asynchronous closes of the stream, releasing resources related to it.
            </para>
            <para>
                For more details, see
                <methodname><link linkend="method-gioinputstream--close">gio.InputStream.close</link></methodname>()
                which is the synchronous version of this call. 
            </para>
            <para>
                When the operation is finished, callback will be called. You can then call
                <methodname><link linkend="method-gioinputstream--close-finish">gio.InputStream.close_finish</link></methodname>()
                to get the result of the operation.
            </para>
        </refsect2>

        <refsect2 id="method-gioinputstream--close-finish">
            <title>gio.InputStream.close_finish</title>

            <programlisting><methodsynopsis language="python">
                <methodname>close_finish</methodname>
                <methodparam><parameter role="keyword">result</parameter></methodparam>
            </methodsynopsis></programlisting>
            
            <variablelist>
                <varlistentry>
                  <term><parameter role="keyword">result</parameter>&nbsp;:</term>
                  <listitem><simpara>a <link linkend="class-gioasyncresult"><classname>gio.AsyncResult</classname></link>.
                  </simpara></listitem>
                </varlistentry>
                <varlistentry>
                    <term><emphasis>Returns</emphasis>&nbsp;:</term>
                    <listitem><simpara><literal>True</literal> if the stream was closed successfully.
                    </simpara></listitem>
                </varlistentry>
            </variablelist>
    
            <para>
                The <methodname>close_finish</methodname>() method finishes an asynchronous
                file append operation started with
                <methodname><link linkend="method-gioinputstream--close-async">gio.InputStream.close_async</link></methodname>().
            </para>
        </refsect2>

        <refsect2 id="method-gioinputstream--has-pending">
            <title>gio.InputStream.has_pending</title>

            <programlisting><methodsynopsis language="python">
                <methodname>has_pending</methodname>
                <methodparam></methodparam>
            </methodsynopsis></programlisting>
            
            <variablelist>
                <varlistentry>
                    <term><emphasis>Returns</emphasis>&nbsp;:</term>
                    <listitem><simpara><literal>True</literal> if stream has pending actions.
                    </simpara></listitem>
                </varlistentry>
            </variablelist>
    
            <para>
                The <methodname>has_pending</methodname>() method checks if an input stream has pending actions.
            </para>
        </refsect2>

        <refsect2 id="method-gioinputstream--is-closed">
            <title>gio.InputStream.is_closed</title>

            <programlisting><methodsynopsis language="python">
                <methodname>is_closed</methodname>
                <methodparam></methodparam>
            </methodsynopsis></programlisting>
            
            <variablelist>
                <varlistentry>
                    <term><emphasis>Returns</emphasis>&nbsp;:</term>
                    <listitem><simpara><literal>True</literal> if the stream is closed.
                    </simpara></listitem>
                </varlistentry>
            </variablelist>
    
            <para>
                The <methodname>is_closed</methodname>() method checks if an input stream is closed.
            </para>
        </refsect2>

        <refsect2 id="method-gioinputstream--read">
            <title>gio.InputStream.read</title>

            <programlisting><methodsynopsis language="python">
                <methodname>read</methodname>
                <methodparam><parameter role="keyword">count</parameter><initializer>-1</initializer></methodparam>
                <methodparam><parameter role="keyword">cancellable</parameter><initializer>None</initializer></methodparam>
            </methodsynopsis></programlisting>
            
            <variablelist>
                <varlistentry>
                  <term><parameter role="keyword">count</parameter>&nbsp;:</term>
                  <listitem><simpara>optionally the number of bytes that will be read from the stream.
                  </simpara></listitem>
                </varlistentry>
                <varlistentry>
                  <term><parameter role="keyword">cancellable</parameter>&nbsp;:</term>
                  <listitem><simpara>optional
                    <link linkend="class-giocancellable"><classname>gio.Cancellable</classname></link>
                    object, <literal>None</literal> to ignore.
                  </simpara></listitem>
                </varlistentry>
                <varlistentry>
                    <term><emphasis>Returns</emphasis>&nbsp;:</term>
                    <listitem><simpara>The number of bytes read, or -1 on error.
                    </simpara></listitem>
                </varlistentry>
            </variablelist>
    
            <para>
                The <methodname>read</methodname>() method tries to read count bytes from
                the stream into the buffer starting at buffer. Will block during this read.
            </para>
            <para>
                This function is similar to
                <methodname><link linkend="method-gioinputstream--read-part">gio.InputStream.read_part</link></methodname>(),
                except it tries to read as many bytes as requested, only stopping on an error or end of stream.
            </para>
            <para>
                On a successful read of count bytes, or if we reached the end of the stream,
                <literal>True</literal> is returned, and bytes_read is set to the number of bytes read into buffer.
            </para>
            <para>
                If cancellable is not <literal>None</literal>, then the operation can be cancelled by
                triggering the cancellable object from another thread. If the operation was cancelled,
                the error gio.IO_ERROR_CANCELLED will be returned. Cancelling a close will still leave
                the stream closed, but some streams can use a faster close that doesn't block to e.g.
                check errors.
            </para>
            <para>
                If there is an error during the operation <literal>False</literal> is returned and error
                is set to indicate the error status, bytes_read is updated to contain the number of
                bytes read into buffer before the error occurred.
            </para>
        </refsect2>

        <refsect2 id="method-gioinputstream--read-async">
            <title>gio.InputStream.read_async</title>

            <programlisting><methodsynopsis language="python">
                <methodname>read_async</methodname>
                <methodparam><parameter role="keyword">count</parameter></methodparam>
                <methodparam><parameter role="keyword">callback</parameter></methodparam>
                <methodparam><parameter role="keyword">io_priority</parameter><initializer>glib.PRIORITY_DEFAULT</initializer></methodparam>
                <methodparam><parameter role="keyword">cancellable</parameter><initializer>None</initializer></methodparam>
                <methodparam><parameter role="keyword">user_data</parameter><initializer>None</initializer></methodparam>
            </methodsynopsis></programlisting>
            
            <variablelist>
                <varlistentry>
                    <term><parameter>count</parameter>&nbsp;:</term>
                    <listitem><simpara>the number of bytes that will be read from the stream.
                    </simpara></listitem>
                </varlistentry>
                <varlistentry>
                    <term><parameter>callback</parameter>&nbsp;:</term>
                    <listitem><simpara>a GAsyncReadyCallback to call when the request is satisfied.
                    </simpara></listitem>
                </varlistentry>
                <varlistentry>
                    <term><parameter>io_priority</parameter>&nbsp;:</term>
                    <listitem><simpara>the
                    <xref linkend="glib-priority-constants" endterm="glib-priority-constants-title"></xref>
                    of the request. 
                    </simpara></listitem>
                </varlistentry>
                <varlistentry>
                    <term><parameter>cancellable</parameter>&nbsp;:</term>
                    <listitem><simpara>optional
                    <link linkend="class-giocancellable"><classname>gio.Cancellable</classname></link>
                    object, <literal>None</literal> to ignore.</simpara></listitem>
                </varlistentry>
                <varlistentry>
                    <term><parameter>user_data</parameter>&nbsp;:</term>
                    <listitem><simpara>the data to pass to callback function.
                    </simpara></listitem>
                </varlistentry>
            </variablelist>
    
            <para>
                The <methodname>read_async</methodname>() method requests an asynchronous read
                of count bytes from the stream into the buffer.
            </para>
            <para>
                For more details, see
                <methodname><link linkend="method-gioinputstream--read">gio.InputStream.read</link></methodname>()
                which is the synchronous version of this call. 
            </para>
            <para>
                When the operation is finished, callback will be called. You can then call
                <methodname><link linkend="method-gioinputstream--read-finish">gio.InputStream.read_finish</link></methodname>()
                to get the result of the operation.
            </para>
            <para>
                During an async request no other sync and async calls are allowed, and
                will result in gio.IO_ERROR_PENDING errors.
            </para>
            <para>
                A value of count larger than G_MAXSSIZE will cause a gio.IO_ERROR_INVALID_ARGUMENT error.
            </para>
            <para>
                On success, the number of bytes read into the buffer will be passed to the callback.
                It is not an error if this is not the same as the requested size, as it can happen e.g.
                near the end of a file, but generally we try to read as many bytes as requested. Zero
                is returned on end of file (or if count is zero), but never otherwise.
            </para>
            <para>
                Any outstanding i/o request with higher priority (lower numerical value) will be
                executed before an outstanding request with lower priority. Default priority is glib.PRIORITY_DEFAULT.
            </para>
            <para>
                The asyncronous methods have a default fallback that uses threads to implement asynchronicity, so
                they are optional for inheriting classes. However, if you override one you must override all.
            </para>
        </refsect2>

        <refsect2 id="method-gioinputstream--read-finish">
            <title>gio.InputStream.read_finish</title>

            <programlisting><methodsynopsis language="python">
                <methodname>read_finish</methodname>
                <methodparam><parameter role="keyword">result</parameter></methodparam>
            </methodsynopsis></programlisting>
            
            <variablelist>
                <varlistentry>
                  <term><parameter role="keyword">result</parameter>&nbsp;:</term>
                  <listitem><simpara>a <link linkend="class-gioasyncresult"><classname>gio.AsyncResult</classname></link>.
                  </simpara></listitem>
                </varlistentry>
                <varlistentry>
                    <term><emphasis>Returns</emphasis>&nbsp;:</term>
                    <listitem><simpara>The number of bytes read in, or -1 on error.
                    </simpara></listitem>
                </varlistentry>
            </variablelist>
    
            <para>
                The <methodname>read_finish</methodname>() method finishes an asynchronous
                stream read operation started by
                <methodname><link linkend="method-gioinputstream--read-async">gio.InputStream.read_async</link></methodname>().
            </para>
        </refsect2>

        <refsect2 id="method-gioinputstream--read-part">
            <title>gio.InputStream.read_part</title>

            <programlisting><methodsynopsis language="python">
                <methodname>read_part</methodname>
                <methodparam><parameter role="keyword">count</parameter><initializer>-1</initializer></methodparam>
                <methodparam><parameter role="keyword">cancellable</parameter><initializer>None</initializer></methodparam>
            </methodsynopsis></programlisting>
            
            <variablelist>
                <varlistentry>
                  <term><parameter role="keyword">count</parameter>&nbsp;:</term>
                  <listitem><simpara>optionally the number of bytes that will be read from the stream.
                  </simpara></listitem>
                </varlistentry>
                <varlistentry>
                  <term><parameter role="keyword">cancellable</parameter>&nbsp;:</term>
                  <listitem><simpara>optional
                    <link linkend="class-giocancellable"><classname>gio.Cancellable</classname></link>
                    object, <literal>None</literal> to ignore.
                  </simpara></listitem>
                </varlistentry>
                <varlistentry>
                    <term><emphasis>Returns</emphasis>&nbsp;:</term>
                    <listitem><simpara>The number of bytes read, or -1 on error.
                    </simpara></listitem>
                </varlistentry>
            </variablelist>
    
            <para>
                The <methodname>read_part</methodname>() method tries to read count bytes from
                the stream into the buffer starting at buffer. Will block during this read.
            </para>
            <para>
                If count is zero returns zero and does nothing. A value of count larger than
                G_MAXSSIZE will cause a gio.IO_ERROR_INVALID_ARGUMENT error.
            </para>
            <para>
                On success, the number of bytes read into the buffer is returned. It is
                not an error if this is not the same as the requested size, as it can
                happen e.g. near the end of a file. Zero is returned on end of file
                (or if count is zero), but never otherwise.
            </para>
            <para>
               If cancellable is not <literal>None</literal>, then the operation can be cancelled by
                triggering the cancellable object from another thread. If the operation was cancelled,
                the error gio.IO_ERROR_CANCELLED will be returned. Cancelling a close will still leave
                the stream closed, but some streams can use a faster close that doesn't block to e.g.
                check errors.
            </para>
            <para>
                On error -1 is returned and error is set accordingly.
            </para>
            <note>
                This method roughly corresponds to C GIO g_input_stream_read.
            </note>
        </refsect2>

        <refsect2 id="method-gioinputstream--set-pending">
            <title>gio.InputStream.set_pending</title>

            <programlisting><methodsynopsis language="python">
                <methodname>set_pending</methodname>
                <methodparam></methodparam>
            </methodsynopsis></programlisting>
            
            <variablelist>
                <varlistentry>
                    <term><emphasis>Returns</emphasis>&nbsp;:</term>
                    <listitem><simpara><literal>True</literal> if pending was previously
                    unset and is now set.
                    </simpara></listitem>
                </varlistentry>
            </variablelist>
    
            <para>
                The <methodname>set_pending</methodname>() method sets stream to have actions pending.
                If the pending flag is already set or stream is closed,
                it will return <literal>False</literal> and set error.
            </para>
        </refsect2>

        <refsect2 id="method-gioinputstream--skip">
            <title>gio.InputStream.skip</title>

            <programlisting><methodsynopsis language="python">
                <methodname>skip</methodname>
                <methodparam><parameter role="keyword">count</parameter></methodparam>
                <methodparam><parameter role="keyword">cancellable</parameter><initializer>None</initializer></methodparam>
            </methodsynopsis></programlisting>
            
            <variablelist>
                <varlistentry>
                  <term><parameter role="keyword">count</parameter>&nbsp;:</term>
                  <listitem><simpara>the number of bytes that will be skipped from the stream.
                  </simpara></listitem>
                </varlistentry>
                <varlistentry>
                  <term><parameter role="keyword">cancellable</parameter>&nbsp;:</term>
                  <listitem><simpara>optional
                    <link linkend="class-giocancellable"><classname>gio.Cancellable</classname></link>
                    object, <literal>None</literal> to ignore.
                  </simpara></listitem>
                </varlistentry>
                <varlistentry>
                    <term><emphasis>Returns</emphasis>&nbsp;:</term>
                    <listitem><simpara>The number of bytes skipped, or -1 on error
                    </simpara></listitem>
                </varlistentry>
            </variablelist>
    
            <para>
                The <methodname>skip</methodname>() method tries to skip count bytes
                from the stream. Will block during the operation.
            </para>
            <para>
                This is identical to
                <methodname><link linkend="method-gioinputstream--read">read</link></methodname>(),
                from a behaviour standpoint, but the bytes that are skipped are not
                returned to the user. Some streams have an implementation that is more
                efficient than reading the data.
            </para>
            <para>
                This function is optional for inherited classes, as the default implementation emulates it using read.
            </para>
            <para>
               If cancellable is not <literal>None</literal>, then the operation can be cancelled by
                triggering the cancellable object from another thskip. If the operation was cancelled,
                the error gio.IO_ERROR_CANCELLED will be returned. Cancelling a close will still leave
                the stream closed, but some streams can use a faster close that doesn't block to e.g.
                check errors.
            </para>
        </refsect2>

        <refsect2 id="method-gioinputstream--skip-async">
            <title>gio.InputStream.skip_async</title>

            <programlisting><methodsynopsis language="python">
                <methodname>skip_async</methodname>
                <methodparam><parameter role="keyword">count</parameter></methodparam>
                <methodparam><parameter role="keyword">callback</parameter></methodparam>
                <methodparam><parameter role="keyword">io_priority</parameter><initializer>glib.PRIORITY_DEFAULT</initializer></methodparam>
                <methodparam><parameter role="keyword">cancellable</parameter><initializer>None</initializer></methodparam>
                <methodparam><parameter role="keyword">user_data</parameter><initializer>None</initializer></methodparam>
            </methodsynopsis></programlisting>
            
            <variablelist>
                <varlistentry>
                    <term><parameter>count</parameter>&nbsp;:</term>
                    <listitem><simpara>the number of bytes that will be skipped from the stream.
                    </simpara></listitem>
                </varlistentry>
                <varlistentry>
                    <term><parameter>callback</parameter>&nbsp;:</term>
                    <listitem><simpara>a GAsyncskipyCallback to call when the request is satisfied.
                    </simpara></listitem>
                </varlistentry>
                <varlistentry>
                    <term><parameter>io_priority</parameter>&nbsp;:</term>
                    <listitem><simpara>the
                    <xref linkend="glib-priority-constants" endterm="glib-priority-constants-title"></xref>
                    of the request. 
                    </simpara></listitem>
                </varlistentry>
                <varlistentry>
                    <term><parameter>cancellable</parameter>&nbsp;:</term>
                    <listitem><simpara>optional
                    <link linkend="class-giocancellable"><classname>gio.Cancellable</classname></link>
                    object, <literal>None</literal> to ignore.</simpara></listitem>
                </varlistentry>
                <varlistentry>
                    <term><parameter>user_data</parameter>&nbsp;:</term>
                    <listitem><simpara>the data to pass to callback function.
                    </simpara></listitem>
                </varlistentry>
            </variablelist>
    
            <para>
                The <methodname>skip_async</methodname>() method request an asynchronous
                skip of count bytes from the stream.
            </para>
            <para>
                For more details, see
                <methodname><link linkend="method-gioinputstream--skip">gio.InputStream.skip</link></methodname>()
                which is the synchronous version of this call. 
            </para>
            <para>
                When the operation is finished, callback will be called. You can then call
                <methodname><link linkend="method-gioinputstream--skip-finish">gio.InputStream.skip_finish</link></methodname>()
                to get the result of the operation.
            </para>
            <para>
                During an async request no other sync and async calls are allowed, and
                will result in gio.IO_ERROR_PENDING errors.
            </para>
            <para>
                A value of count larger than G_MAXSSIZE will cause a gio.IO_ERROR_INVALID_ARGUMENT error.
            </para>
            <para>
                On success, the number of bytes skipped will be passed to the callback. It is
                not an error if this is not the same as the requested size, as it can happen
                e.g. near the end of a file, but generally we try to skip as many bytes as requested.
                Zero is returned on end of file (or if count is zero), but never otherwise.
            </para>
            <para>
                Any outstanding i/o request with higher priority (lower numerical value) will be
                executed before an outstanding request with lower priority. Default priority is glib.PRIORITY_DEFAULT.
            </para>
            <para>
                The asyncronous methods have a default fallback that uses thskips to implement asynchronicity, so
                they are optional for inheriting classes. However, if you override one you must override all.
            </para>
        </refsect2>

        <refsect2 id="method-gioinputstream--skip-finish">
            <title>gio.InputStream.skip_finish</title>

            <programlisting><methodsynopsis language="python">
                <methodname>skip_finish</methodname>
                <methodparam><parameter role="keyword">result</parameter></methodparam>
            </methodsynopsis></programlisting>
            
            <variablelist>
                <varlistentry>
                  <term><parameter role="keyword">result</parameter>&nbsp;:</term>
                  <listitem><simpara>a <link linkend="class-gioasyncresult"><classname>gio.AsyncResult</classname></link>.
                  </simpara></listitem>
                </varlistentry>
                <varlistentry>
                    <term><emphasis>Returns</emphasis>&nbsp;:</term>
                    <listitem><simpara>The number of bytes skipped in, or -1 on error.
                    </simpara></listitem>
                </varlistentry>
            </variablelist>
    
            <para>
                The <methodname>skip_finish</methodname>() method finishes an asynchronous
                stream skip operation started by
                <methodname><link linkend="method-gioinputstream--skip-async">gio.InputStream.skip_async</link></methodname>().
            </para>
        </refsect2>
    </refsect1>
</refentry>