GeezerVison is showing github.com — python-xlib.github.io/python-xlib_6.html at master · python-xlib/python-xlib.github.io

Expand file tree

python-xlib_6.html

Copy path

More file actions

Latest commit

History

128 lines (119 loc) · 6.4 KB

python-xlib_6.html

Copy path

File metadata and controls

128 lines (119 loc) · 6.4 KB

Raw

Copy raw file

Download raw file

Open symbols panel

Edit and raw actions

100

101

102

103

104

105

106

107

108

109

110

111

112

113

114

115

116

117

118

119

120

121

122

123

124

125

126

127

128

<!DOCTYPE html PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN" "http://www.w3.org/TR/html4/loose.dtd">

<html>

<!-- Created on September 16, 2020 by texi2html 5.0

texi2html was written by:

Lionel Cons <[email protected]> (original author)

Karl Berry <[email protected]>

Olaf Bachmann <[email protected]>

and many others.

Maintained by: Many creative people.

Send bugs and suggestions to <[email protected]>

-->

<head>

<title>The Python X Library: 4 Error Handling</title>

<!--

a.summary-letter {text-decoration: none}

blockquote.smallquotation {font-size: smaller}

div.display {margin-left: 3.2em}

div.example {margin-left: 3.2em}

div.lisp {margin-left: 3.2em}

div.smalldisplay {margin-left: 3.2em}

div.smallexample {margin-left: 3.2em}

div.smalllisp {margin-left: 3.2em}

pre.display {font-family: serif}

pre.format {font-family: serif}

pre.menu-comment {font-family: serif}

pre.menu-preformatted {font-family: serif}

pre.smalldisplay {font-family: serif; font-size: smaller}

pre.smallexample {font-size: smaller}

pre.smallformat {font-family: serif; font-size: smaller}

pre.smalllisp {font-size: smaller}

span.nocodebreak {white-space:pre}

span.nolinebreak {white-space:pre}

span.roman {font-family:serif; font-weight:normal}

span.sansserif {font-family:sans-serif; font-weight:normal}

ul.no-bullet {list-style: none}

-->

</style>

</head>

<td valign="middle" align="left">[<a href="python-xlib_toc.html#SEC_Contents" title="Table of contents">Contents</a>]</td>

<td valign="middle" align="left">[Index]</td>

</tr></table>

<hr>

<h1 class="chapter">4 Error Handling</h1>

<p>If an X object method generates an error, it will be handled in one of two

different ways depending on the kind of method. Errors are represented

by X error objects in the Xlib.

</p>

<p>If the method <em>does not</em> return data, the error will most likely be

detected after the method has returned. All methods which does not

return data has a parameter called <code>onerror</code>, which can be used to

provide a error handler for any error generated by this method.

</p>

<p>The error handler is called with to arguments: the error object and the

low-level request object. The error <em>must not</em> do call any X

object methods. If that is necessary, the error handler must store the

error away for later retrieval. The class <code>error.CatchError</code> is

provided for this purpose.

</p>

<p>If no error handler is given when calling a method which generates an

error, the error will be passed to the default error handler. If no

default error handler is specified, the error is simply printed on

<code>sys.stderr</code>.

</p>

<p>If the method <em>does</em> return data, the error will make it impossible

for it to return any valid data. An exception is raised with the error

object as the exception value. It is not passed to any error handlers.

</p>

<tr><td align="left" valign="top"><a href="python-xlib_7.html#X-Error-Classes">4.1 X Error Classes</a></td><td>  </td><td align="left" valign="top"> X error class hierarchy.

</td></tr>

<tr><td align="left" valign="top"><a href="python-xlib_8.html#CatchError">4.2 CatchError</a></td><td>  </td><td align="left" valign="top"> Error handler class.

</td></tr>

</table>

<hr>

<td valign="middle" align="left">[<a href="python-xlib_toc.html#SEC_Contents" title="Table of contents">Contents</a>]</td>

<td valign="middle" align="left">[Index]</td>

</tr></table>

<p>

This document was generated on <i>September 16, 2020</i> using <a href="http://www.nongnu.org/texi2html/"><i>texi2html 5.0</i></a>.

</font>

<br>

</p>

</body>

</html>