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Error Context Display
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<h1>
HTML_CSS : The Definitive Guide
</h1>
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Error Context Display
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Chapter 9. Error Handler
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<div class="sect1" lang="en" xml:lang="en">
<div class="titlepage">
<h2 class="title c1">
<a name="id4800246" id="id4800246"></a>Error Context Display
</h2>
</div>
<p>
In some cases, you may want to customize error generation. For
instance, for each error (basic/exception), it is useful to include
file, line number, and class/function context information in order to
trace it. The default option will be sufficient for most cases but you
want perhaps customize the output format (render) of context
information.
</p>
<p>
With this example we will change display and log renders.
</p>
<div class="php c2">
<ol>
<li class="li1">
<div class="de1">
<span class="kw2"><?php</span>
</div>
</li>
<li class="li1">
<div class="de1">
<span class="kw1">require_once</span> <span class=
"st0">'HTML/CSS.php'</span>;
</div>
</li>
<li class="li1">
<div class="de1">
</div>
</li>
<li class="li1">
<div class="de1">
<span class="re0">$displayConfig</span> = <span class=
"kw3">array</span><span class="br0">(</span>
</div>
</li>
<li class="li1">
<div class="de1">
<span class="st0">'lineFormat'</span> =>
<span class="st0">'<b>%1$s</b>: %2$s<br
/>%3$s'</span>,
</div>
</li>
<li class="li1">
<div class="de1">
<span class="st0">'contextFormat'</span>
=> <span class="st0">'<b>File:</b>
%1$s <br />'</span>
</div>
</li>
<li class="li1">
<div class="de1">
. <span class="st0">'<b>Line:</b>
%2$s <br />'</span>
</div>
</li>
<li class="li1">
<div class="de1">
. <span class=
"st0">'<b>Function:</b> %3$s '</span>
</div>
</li>
<li class="li1">
<div class="de1">
<span class="br0">)</span>;
</div>
</li>
<li class="li1">
<div class="de1">
<span class="re0">$logConfig</span> = <span class=
"kw3">array</span><span class="br0">(</span>
</div>
</li>
<li class="li1">
<div class="de1">
<span class="st0">'lineFormat'</span> =>
<span class="st0">'%1$s %2$s [%3$s] %4$s'</span>,
</div>
</li>
<li class="li1">
<div class="de1">
<span class="st0">'timeFormat'</span> =>
<span class="st0">'%b'</span>
</div>
</li>
<li class="li1">
<div class="de1">
<span class="br0">)</span>;
</div>
</li>
<li class="li1">
<div class="de1">
</div>
</li>
<li class="li1">
<div class="de1">
<span class="re0">$prefs</span> = <span class=
"kw3">array</span><span class="br0">(</span>
</div>
</li>
<li class="li1">
<div class="de1">
<span class="st0">'handler'</span> =>
<span class="kw3">array</span><span class=
"br0">(</span><span class="st0">'display'</span> =>
<span class="re0">$displayConfig</span>,
</div>
</li>
<li class="li1">
<div class="de1">
<span class="st0">'log'</span>
=> <span class="re0">$logConfig</span>
</div>
</li>
<li class="li1">
<div class="de1">
<span class="br0">)</span><span class="br0">)</span>;
</div>
</li>
<li class="li1">
<div class="de1">
</div>
</li>
<li class="li1">
<div class="de1">
<span class="re0">$css</span> = <span class="kw2">new</span>
HTML_CSS<span class="br0">(</span><span class="kw2">null</span>,
<span class="re0">$prefs</span><span class="br0">)</span>;
</div>
</li>
<li class="li1">
<div class="de1">
<span class="co1">// ...</span>
</div>
</li>
<li class="li1">
<div class="de1">
<span class="re0">$result</span> = <span class=
"re0">$css</span>-><span class=
"me1">setStyle</span><span class="br0">(</span><span class=
"st0">'div'</span>, <span class="st0">'color'</span>,
<span class="nu0">5</span><span class="br0">)</span>;
</div>
</li>
<li class="li1">
<div class="de1">
<span class="kw2">?></span>
</div>
</li>
</ol>
</div>
<p>
Display render will give something like:
</p>
<div class="informalexample screenco">
<pre class="screen">
Exception<a name="error.2.level" id="error.2.level"></a><img src=
"img/callouts/1.gif" alt="1" border=
"0" />: invalid input, parameter #3 "$value" was expecting "string", instead got "integer"<a name="error.2.message"
id="error.2.message"></a><img src="img/callouts/2.gif" alt="2" border="0" />
File: [path_to]\[filename] <a name="error.2.context" id=
"error.2.context"></a><img src="img/callouts/3.gif" alt="3" border="0" />
Line: 22 <a name="error.2.context" id="error.2.context"></a><img src=
"img/callouts/3.gif" alt="3" border="0" />
Function: html_css->setstyle <a name="error.2.context" id=
"error.2.context"></a><img src="img/callouts/3.gif" alt="3" border="0" />
</pre>
<div class="calloutlist">
<table border="0" summary="Callout list">
<tr>
<td width="5%" valign="top" align="left">
<a href="#error.2.level"><img src="img/callouts/1.gif" alt="1"
border="0" /></a>
</td>
<td valign="top" align="left">
<p>
error level
</p>
</td>
</tr>
<tr>
<td width="5%" valign="top" align="left">
<a href="#error.2.message"><img src="img/callouts/2.gif" alt=
"2" border="0" /></a>
</td>
<td valign="top" align="left">
<p>
message body with context informations
</p>
</td>
</tr>
<tr>
<td width="5%" valign="top" align="left">
<a href="#error.2.context"><img src="img/callouts/3.gif" alt=
"3" border="0" /></a>
</td>
<td valign="top" align="left">
<p>
call context (file, line, function)
</p>
</td>
</tr>
</table>
</div>
</div>
<p>
Log render will give something like:
</p>
<div class="informalexample screenco">
<pre class="screen">
Jun 127.0.0.1<a name="error.3.context" id="error.3.context"></a><img src=
"img/callouts/1.gif" alt="1" border="0" /> [exception<a name="error.3.level"
id="error.3.level"></a><img src="img/callouts/2.gif" alt="2" border=
"0" />] invalid input, parameter #3 "$value" was expecting "string", instead got "integer"<a name="error.3.message"
id="error.3.message"></a><img src="img/callouts/3.gif" alt="3" border="0" />
</pre>
<div class="calloutlist">
<table border="0" summary="Callout list">
<tr>
<td width="5%" valign="top" align="left">
<a href="#error.3.context"><img src="img/callouts/1.gif" alt=
"1" border="0" /></a>
</td>
<td valign="top" align="left">
<p>
client ip address and execution date
</p>
</td>
</tr>
<tr>
<td width="5%" valign="top" align="left">
<a href="#error.3.level"><img src="img/callouts/2.gif" alt="2"
border="0" /></a>
</td>
<td valign="top" align="left">
<p>
error level
</p>
</td>
</tr>
<tr>
<td width="5%" valign="top" align="left">
<a href="#error.3.message"><img src="img/callouts/3.gif" alt=
"3" border="0" /></a>
</td>
<td valign="top" align="left">
<p>
message body with context informations
</p>
</td>
</tr>
</table>
</div>
</div>
<div class="note c3">
<table border="0" summary="Note">
<tr>
<td rowspan="2" align="center" valign="top" width="48">
<img alt="[Note]" src="img/admons/note.png" />
</td>
<th align="left">
Note
</th>
</tr>
<tr>
<td align="left" valign="top">
To have both display and log output, check the <code class=
"filename">php.ini</code><span class=
"emphasis"><em>display_errors</em></span> and <span class=
"emphasis"><em>log_errors</em></span> values : must be set to
<code class="constant">TRUE</code>.
</td>
</tr>
</table>
</div>
<p>
Let review, step by step, how to get such results.
</p>
<p>
Remember that with default classes, there are two drivers :
<span class="emphasis"><em>display</em></span> and <span class=
"emphasis"><em>log</em></span> that have both their own configuration
parameters. You can override these parameters values with the
<span class="bold"><strong>handler</strong></span> entry in the hash of
second argument of the HTML_CSS class constructor.
</p>
<p>
We did it here with the <em class="parameter"><code>$prefs</code></em>
variable; its a two keys associative array. First key <span class=
"emphasis"><em>display</em></span> defines the display driver values,
and the second key <span class="emphasis"><em>log</em></span> defines
the log driver values.
</p>
<p>
Review the <span class="emphasis"><em>display</em></span> driver custom
values. Only two keys: <span class="simplelist">lineFormat,
contextFormat</span> are redefined, thats means remains key
<span class="simplelist">eol</span> keep its default value. See table
below.
</p>
<div class="table">
<a name="id4800725" id="id4800725"></a>
<p class="title c4">
Table 9.2. Display driver configuration parameters
</p>
<table summary="Display driver configuration parameters" border="1">
<colgroup>
<col />
<col />
<col />
<col />
</colgroup>
<thead>
<tr>
<th>
Parameter
</th>
<th>
Type
</th>
<th>
Default
</th>
<th>
Description
</th>
</tr>
</thead>
<tbody>
<tr>
<td>
eol
</td>
<td>
string
</td>
<td>
<br />\n
</td>
<td>
The end-on-line character sequence
</td>
</tr>
<tr>
<td>
lineFormat
</td>
<td>
string
</td>
<td>
<b>%1$s</b>: %2$s %3$s
</td>
<td>
Log line format specification:
<div class="itemizedlist">
<ul type="disc">
<li>1$ = error level
</li>
<li>2$ = error message (body)
</li>
<li>3$ = error context
</li>
</ul>
</div>
</td>
</tr>
<tr>
<td>
contextFormat
</td>
<td>
string
</td>
<td>
in <b>%3$s</b> (file <b>%1$s</b> on
line <b>%2$s</b>)
</td>
<td>
Context format (class, file, line) specification:
<div class="itemizedlist">
<ul type="disc">
<li>1$ = script file name
</li>
<li>2$ = line in script file
</li>
<li>3$ = class/method names
</li>
</ul>
</div>
</td>
</tr>
</tbody>
</table>
</div>
<div class="tip c3">
<table border="0" summary="Tip">
<tr>
<td rowspan="2" align="center" valign="top" width="48">
<img alt="[Tip]" src="img/admons/tip.png" />
</td>
<th align="left">
Tip
</th>
</tr>
<tr>
<td align="left" valign="top">
If you don't wish to see context information in the error
message, then remove the parameter %3$ in the <span class=
"emphasis"><em>lineFormat</em></span> option even if <span class=
"emphasis"><em>contextFormat</em></span> is set.
</td>
</tr>
</table>
</div>
<p>
Review now the <span class="emphasis"><em>log</em></span> driver custom
values. Only two keys <span class="simplelist">lineFormat,
timeFormat</span> are redefined, thats means six remains keys
<span class="simplelist">eol, contextFormat, ident, message_type,
destination, extra_headers</span> keep their default values. See table
below.
</p>
<div class="table">
<a name="id4800916" id="id4800916"></a>
<p class="title c4">
Table 9.3. Log driver configuration parameters
</p>
<table summary="Log driver configuration parameters" border="1">
<colgroup>
<col />
<col />
<col />
<col />
</colgroup>
<thead>
<tr>
<th>
Parameter
</th>
<th>
Type
</th>
<th>
Default
</th>
<th>
Description
</th>
</tr>
</thead>
<tbody>
<tr>
<td>
eol
</td>
<td>
string
</td>
<td>
\n
</td>
<td>
The end-on-line character sequence
</td>
</tr>
<tr>
<td>
lineFormat
</td>
<td>
string
</td>
<td>
%1$s %2$s [%3$s] %4$s %5$s
</td>
<td>
Log line format specification:
<div class="itemizedlist">
<ul type="disc">
<li>$1 = time error
</li>
<li>2$ = ident (client ip)
</li>
<li>3$ = error level
</li>
<li>4$ = error message (body)
</li>
<li>5$ = error context
</li>
</ul>
</div>
</td>
</tr>
<tr>
<td>
contextFormat
</td>
<td>
string
</td>
<td>
in %3$s (file %1$s on line %2$s)
</td>
<td>
Context format (class, file, line) specification:
<div class="itemizedlist">
<ul type="disc">
<li>1$ = script file name
</li>
<li>2$ = line in script file
</li>
<li>3$ = class/method names
</li>
</ul>
</div>
</td>
</tr>
<tr>
<td>
timeFormat
</td>
<td>
string
</td>
<td>
%b %d %H:%M:%S
</td>
<td>
Time stamp format used by <a class="external" href=
"http://www.php.net/manual-lookup.php?pattern=strftime" title=
"http://www.php.net/manual-lookup.php?pattern=strftime">strftime</a>
</td>
</tr>
<tr>
<td>
ident
</td>
<td>
string
</td>
<td>
REMOTE_ADDR
</td>
<td>
Client IP
</td>
</tr>
<tr>
<td>
message_type
</td>
<td>
string
</td>
<td>
3
</td>
<td>
Destination type used by <a class="external" href=
"http://www.php.net/manual-lookup.php?pattern=error_log" title=
"http://www.php.net/manual-lookup.php?pattern=error_log">error_log</a>
</td>
</tr>
<tr>
<td>
destination
</td>
<td>
string
</td>
<td>
html_css_error.log
</td>
<td>
Destination name used by <a class="external" href=
"http://www.php.net/manual-lookup.php?pattern=error_log" title=
"http://www.php.net/manual-lookup.php?pattern=error_log">error_log</a>
</td>
</tr>
<tr>
<td>
extra_headers
</td>
<td>
string
</td>
<td>
<code class="constant">NULL</code>
</td>
<td>
Extra headers depending of destination type
</td>
</tr>
</tbody>
</table>
</div>
<div class="tip c3">
<table border="0" summary="Tip">
<tr>
<td rowspan="2" align="center" valign="top" width="48">
<img alt="[Tip]" src="img/admons/tip.png" />
</td>
<th align="left">
Tip
</th>
</tr>
<tr>
<td align="left" valign="top">
If you don't wish to see context information in the error
message, then remove the parameter %5$ in the <span class=
"emphasis"><em>lineFormat</em></span> option even if <span class=
"emphasis"><em>contextFormat</em></span> is set.
</td>
</tr>
</table>
</div>
</div>
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<td align="left">
HTML_CSS : The Definitive Guide
</td>
<td align="right">
v 1.1.3 : February 18, 2007
</td>
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