| <html><head><meta http-equiv="Content-Type" content="text/html; charset=UTF-8"><title>try</title><link rel="stylesheet" type="text/css" href="rivet.css"><meta name="generator" content="DocBook XSL Stylesheets Vsnapshot"><link rel="home" href="index.html" title="Apache Rivet 3.2"><link rel="up" href="commands.html" title="Rivet Tcl Commands and Variables"><link rel="prev" href="thread_id.html" title="thread_id"><link rel="next" href="unescape_string.html" title="unescape_string"></head><body bgcolor="white" text="black" link="#0000FF" vlink="#840084" alink="#0000FF"><div class="navheader"><table width="100%" summary="Navigation header"><tr><th colspan="3" align="center">try</th></tr><tr><td width="20%" align="left"><a accesskey="p" href="thread_id.html"><img src="images/prev.png" alt="Prev"></a> </td><th width="60%" align="center">Rivet Tcl Commands and Variables</th><td width="20%" align="right"> <a accesskey="n" href="unescape_string.html"><img src="images/next.png" alt="Next"></a></td></tr></table></div><div class="refentry"><div class="refentry.separator"><hr></div><a name="try"></a><div class="titlepage"></div><div class="refnamediv"><h2>Name</h2><p>try — |
| Catch error and exception conditions |
| </p></div><div class="refsynopsisdiv"><h2>Synopsis</h2><div class="cmdsynopsis" style="width:80%"><div style="border: 1px solid #282; margin:1ex ; padding:.4ex; padding-left: 0.8ex; word-spacing:1ex "><span style="font-weight:bold ; font-family:monospace">::rivet::try</span> ?<span style="font-family:monospace; font-weight: bold;">script</span>? ?<span style="font-family:monospace; font-weight: bold;">script</span>? ?<span style="font-family:monospace; font-weight: bold;"><em class="replaceable"><code>handlers</code></em></span>? ?<span style="font-family:monospace; font-weight: bold;"><em class="replaceable"><code>finally script</code></em></span>?</div></div></div><div class="refsect1"><a name="idm1636"></a><h2>Description</h2><p style="width:90%"> |
| <span style="font-family:monospace"><span class="command"><strong>::rivet::try</strong></span></span> wraps the core language |
| command and simply traps exceptions that might have raised |
| by <span style="font-family:monospace"><span class="command"><strong>::rivet::abort_page</strong></span></span> and |
| <span style="font-family:monospace"><span class="command"><strong>::rivet::exit</strong></span></span> to throw them again and |
| thus causing <span style="font-family:monospace"><span class="command"><strong>AbortScript</strong></span></span> to be executed. |
| </p><p style="width:90%"> |
| If neither <span style="font-family:monospace"><span class="command"><strong>::rivet::abort_page</strong></span></span> nor |
| <span style="font-family:monospace"><span class="command"><strong>::rivet::exit</strong></span></span> are called from ?<span style="font-family:monospace; font-weight: bold;">script</span>? |
| then any handlers specified in the command are tested for execution. |
| Thus <span style="font-family:monospace"><span class="command"><strong>::rivet::try</strong></span></span> can transparently be used |
| as a replacement for Tcl's own <span style="font-family:monospace"><span class="command"><strong>try</strong></span></span> and it's needed |
| if you want ?<span style="font-family:monospace; font-weight: bold;">script</span>? to safely bail out to <span style="font-family:monospace"><span class="command"><strong>AbortScript</strong></span></span> |
| </p><div class="note" style="margin-left: 0.5in; margin-right: 0.5in;"><table border="0" summary="Note"><tr><td rowspan="2" align="center" valign="top" width="25"><img alt="[Note]" src="images/note.png"></td><th align="left">Note</th></tr><tr><td align="left" valign="top"> |
| This command is not exported from the <span style="font-family:monospace"><span class="command"><strong>::rivet</strong></span></span> namespace and therefore has |
| to be fully qualified. |
| </td></tr></table></div><p style="width:90%"> |
| This script shows how <span style="font-family:monospace"><span class="command"><strong>::rivet:try</strong></span></span> |
| handles different exceptions or errors. You can drive this script |
| within mod_rivet adding the arguments fail or abort or exit to its URL. |
| You can handle the <span class="quote">“<span class="quote">exit</span>”</span> and <span class="quote">“<span class="quote">abort</span>”</span> cases with |
| an <span style="font-family:monospace"><span class="command"><strong>AbortScript</strong></span></span>. |
| See <a class="xref" href="directives.html" title="Apache Rivet 3.2 Configuration">the section called “Apache Rivet 3.2 Configuration”</a> |
| </p><pre class="programlisting"><html><? |
| ::rivet::try { |
| if {[::rivet::var_qs exists exit]} { |
| ::rivet::exit [::rivet::var_qs get exit] |
| } elseif {[::rivet::var_qs exists abort]} { |
| ::rivet::abort_page [::rivet::var_qs get abort] |
| } elseif {[::rivet::var_qs exists fail]} { |
| # this is just a non existent command |
| wrong_command |
| } else { |
| puts "<b>OK</b>" |
| } |
| |
| } on error {e o} { |
| puts "catching error -&gt; $e<br/>" |
| dict for {fd fv} $o { |
| |
| puts "$fd --&gt;&gt; $fv<br/>" |
| |
| } |
| } |
| ?></html></pre><p style="width:90%"> |
| Placing this code in a file (try.rvt) on the |
| web server <span class="emphasis"><em>DocumentRoot</em></span> |
| directory and setting for example the browser |
| to <span style="font-family:monospace"><span class="command"><strong>http://localhost/try.rvt?fail=1</strong></span></span>. |
| </p><pre class="programlisting">catching error -> invalid command name "wrong_command" |
| -errorcode -->> TCL LOOKUP COMMAND wrong_command |
| -code -->> 1 |
| -level -->> 0 |
| -errorstack -->> INNER {invokeStk1 wrong_command} UP 1 |
| -errorinfo -->> invalid command name "wrong_command" while executing "wrong_command" ("::try" body line 9) |
| -errorline -->> 9</pre></div></div><div class="navfooter"><hr><table width="100%" summary="Navigation footer"><tr><td width="40%" align="left"><a accesskey="p" href="thread_id.html"><img src="images/prev.png" alt="Prev"></a> </td><td width="20%" align="center"><a accesskey="u" href="commands.html"><img src="images/up.png" alt="Up"></a></td><td width="40%" align="right"> <a accesskey="n" href="unescape_string.html"><img src="images/next.png" alt="Next"></a></td></tr><tr><td width="40%" align="left" valign="top">thread_id </td><td width="20%" align="center"><a accesskey="h" href="index.html"><img src="images/home.png" alt="Home"></a></td><td width="40%" align="right" valign="top"> unescape_string</td></tr></table></div></body></html> |
