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<property name="doc(title)">Documenting Tcl Files: Page Contracts and Libraries</property>
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<div class="sect1">
<div class="titlepage"><div><div><h2 class="title" style="clear: both">
<a name="tcl-doc" id="tcl-doc"></a>Documenting Tcl Files: Page Contracts and
Libraries</h2></div></div></div><div class="authorblurb">
<p>By <a class="ulink" href="mailto:jsalz\@mit.edu" target="_top">Jon Salz</a> on 3 July 2000</p>
OpenACS docs are written by the named authors, and may be edited by
OpenACS documentation staff.</div><div class="itemizedlist"><ul class="itemizedlist" style="list-style-type: disc;"><li class="listitem"><p>Tcl procedures:
/packages/acs-kernel/tcl-documentation-procs.tcl</p></li></ul></div><div class="sect2">
<div class="titlepage"><div><div><h3 class="title">
<a name="tcl-doc-bigpicture" id="tcl-doc-bigpicture"></a>The Big Picture</h3></div></div></div><p>In versions of the OpenACS prior to 3.4, <a class="ulink" href="/doc/standards" target="_top">the standard place</a> to document
Tcl files (both Tcl pages and Tcl library files) was in a comment
at the top of the file:</p><pre class="programlisting">
#
# <span class="emphasis"><em>path from server home</em></span>/<span class="emphasis"><em>filename</em></span>
#
# <span class="emphasis"><em>Brief description of the file's purpose</em></span>
#
# <span class="emphasis"><em>author's email address</em></span>, <span class="emphasis"><em>file creation date</em></span>
#
# <a class="ulink" href="http://www.loria.fr/~molli/cvs/doc/cvs_12.html#SEC93" target="_top">$‌Id: tcl-doc.xml,v 1.7.16.1 2023/07/10 08:36:09 gustafn Exp $</a>
#
</pre><p>In addition, the inputs expected by a Tcl page (i.e., form
variables) would be enumerated in a call to <code class="computeroutput">ad_page_variables</code>, in effect, documenting
the page's argument list.</p><p>The problem with these practices is that the documentation is
only accessible by reading the source file itself. For this reason,
ACS 3.4 introduces a new API for documenting Tcl files and, on top
of that, a web-based user interface for browsing the
documentation:</p><div class="itemizedlist"><ul class="itemizedlist" style="list-style-type: disc;">
<li class="listitem"><p>
<span class="strong"><strong><code class="computeroutput"><a class="link" href="tcl-doc" title="ad_page_contract">ad_page_contract</a></code></strong></span>:
Every Tcl page has a <span class="strong"><strong>contract</strong></span> that explicitly defines
what inputs the page expects (with more precision than <code class="computeroutput">ad_page_variables</code>) and incorporates
metadata about the page (what used to live in the top-of-page
comment). Like <code class="computeroutput">ad_page_variables</code>, <code class="computeroutput">ad_page_contract</code> also sets the specified
variables in the context of the Tcl page.</p></li><li class="listitem"><p>
<span class="strong"><strong><code class="computeroutput"><a class="link" href="tcl-doc" title="ad_library">ad_library</a></code></strong></span>: To be called at
the top of every library file (i.e., all files in the <code class="computeroutput">/tcl/</code> directory under the server root and
<code class="computeroutput">*-procs.tcl</code> files under
<code class="computeroutput">/packages/</code>).</p></li>
</ul></div><p>This has the following benefits:</p><div class="itemizedlist"><ul class="itemizedlist" style="list-style-type: disc;">
<li class="listitem"><p>Facilitates automatic generation of human-readable
documentation.</p></li><li class="listitem"><p>Promotes security, by introducing a standard and automated way
to check inputs to scripts for correctness.</p></li><li class="listitem"><p>Allows graphical designers to determine easily how to customize
sites' UIs, e.g., what properties are available in
templates.</p></li><li class="listitem"><p>Allows the request processor to be intelligent: a script can
specify in its contract which type of abstract document it returns,
and the request processor can transform it automatically into
something useful to a particular user agent. (Don't worry about
this for now - it's not complete for ACS 3.4.)</p></li>
</ul></div>
</div><div class="sect2">
<div class="titlepage"><div><div><h3 class="title">
<a name="tcl-doc-ad-page-contract" id="tcl-doc-ad-page-contract"></a>ad_page_contract</h3></div></div></div><p>Currently <code class="computeroutput">ad_page_contract</code>
serves mostly as a replacement for <code class="computeroutput">ad_page_variables</code>. Eventually, it will be
integrated closely with the documents API so that each script's
contract will document precisely the set of properties available to
graphical designers in templates. (Document API integration is
subject to change, so we don't describe it here yet; for now,
you can just consider <code class="computeroutput">ad_page_contract</code> a newer, better,
documented <code class="computeroutput">ad_page_variables</code>.)</p><p>Let's look at an example usage of <code class="computeroutput">ad_page_contract</code>:</p><pre class="programlisting">
# /packages/acs-kernel/api-doc/www/package-view.tcl
ad_page_contract {
version_id:integer
public_p:optional
kind
{ format "html" }
} {
Shows APIs for a particular package.
\@param version_id the ID of the version whose API to view.
\@param public_p view only public APIs?
\@param kind view the type of API to view. One of <code>procs_files</code>,
<code>procs</code>, <code>content</code>, <code>types</code>, or
<code>gd</code>.
\@param format the format for the documentation. One of <code>html</code> or <code>xml</code>.
\@author Jon Salz (jsalz\@mit.edu)
\@creation-date 3 Jul 2000
\@cvs-id $‌Id$
}
</pre><p>Note that:</p><div class="itemizedlist"><ul class="itemizedlist" style="list-style-type: disc;">
<li class="listitem"><p>
<span class="strong"><strong>By convention, <code class="computeroutput">ad_page_contract</code> should be preceded by a
comment line containing the file's path</strong></span>. The
comment is on line 1, and the contract starts on line 2.</p></li><li class="listitem"><p>
<span class="strong"><strong><code class="computeroutput">ad_page_contract</code></strong></span>'s
first argument is the list of expected arguments from the HTTP
query (<code class="computeroutput">version_id</code>, <code class="computeroutput">public_p</code>, <code class="computeroutput">kind</code>, and <code class="computeroutput">format</code>). Like <code class="computeroutput">ad_page_variables</code>, <code class="computeroutput">ad_page_contract</code> sets the corresponding Tcl
variables when the page is executed.</p></li><li class="listitem"><p>
<span class="strong"><strong>Arguments can have
defaults</strong></span>, specified using the same syntax as in the
Tcl <code class="computeroutput">proc</code> (a two-element list
where the first element is the parameter name and the second
argument is the default value).</p></li><li class="listitem">
<p>
<span class="strong"><strong>Arguments can have
flags</strong></span>, specified by following the name of the query
argument with a colon and one or more of the following strings
(separated by commas):</p><div class="itemizedlist"><ul class="itemizedlist" style="list-style-type: circle;">
<li class="listitem"><p>
<span class="strong"><strong><code class="computeroutput">optional</code></strong></span>: the query
argument doesn't need to be provided; if it's not, the
variable for that argument simply won't be set. For instance,
if I call the script above without a <code class="computeroutput">public_p</code> in the query, then in the page
body <code class="computeroutput">[info exists public_p]</code>
will return 0.</p></li><li class="listitem"><p>
<span class="strong"><strong><code class="computeroutput">integer</code></strong></span>: the argument must
be an integer (<code class="computeroutput">ad_page_contract</code>
will fail and display and error if not). This flag, like the next,
is intended to prevent clients from fudging query arguments to
trick scripts into executing arbitrary SQL.</p></li><li class="listitem"><p>
<span class="strong"><strong><code class="computeroutput">sql_identifier</code></strong></span>: the
argument must be a SQL identifier (i.e., <code class="computeroutput">[string is wordchar $the_query_var]</code> must
return true).</p></li><li class="listitem"><p>
<span class="strong"><strong><code class="computeroutput">trim</code></strong></span>: the argument will be
[string trim]'ed.</p></li><li class="listitem">
<p>
<span class="strong"><strong><code class="computeroutput">multiple</code></strong></span>: the argument may
be specified arbitrarily many times in the query string, and the
variable will be set to a list of all those values (or an empty
list if it's unspecified). This is analogous to the
<code class="computeroutput">-multiple-list</code> flag to
<code class="computeroutput">ad_page_variables</code>, and is
useful for handling form input generated by <code class="computeroutput"><SELECT MULTIPLE></code> tags and
checkboxes.</p><p>For instance, if <code class="computeroutput">dest_user_id:multiple</code> is specified in the
contract, and the query string is</p><pre class="programlisting">
?dest_user_id=913&dest_user_id=891&dest_user_id=9
</pre><p>then <code class="computeroutput">$dest_user_id</code> is set to
<code class="computeroutput">[list 913 891 9]</code>.</p>
</li><li class="listitem">
<p>
<span class="strong"><strong><code class="computeroutput">array</code></strong></span>: the argument may be
specified arbitrarily many times in the query string, with
parameter names with suffixes like <code class="computeroutput">_1</code>, <code class="computeroutput">_2</code>,
<code class="computeroutput">_3</code>, etc. The variable is set to
a list of all those values (or an empty list if none are
specified).</p><p>For instance, if <code class="computeroutput">dest_user_id:array</code> is specified in the
contract, and the query string is</p><pre class="programlisting">
?dest_user_id_0=913&dest_user_id_1=891&dest_user_id_2=9
</pre><p>then <code class="computeroutput">$dest_user_id</code> is set to
<code class="computeroutput">[list 913 891 9]</code>.</p>
</li>
</ul></div>
</li><li class="listitem">
<p>
<span class="strong"><strong>You can provide structured,
HTML-formatted documentation for your contract</strong></span>.
Note that format is derived heavily from Javadoc: a general
description of the script's functionality, followed optionally
by a series of named attributes tagged by at symbols (<code class="computeroutput">\@</code>). You are encouraged to provide:</p><div class="itemizedlist"><ul class="itemizedlist" style="list-style-type: circle;">
<li class="listitem"><p>A description of the functionality of the page. If the
description contains more than one sentence, the first sentence
should be a brief summary.</p></li><li class="listitem">
<p>A <span class="strong"><strong><code class="computeroutput">\@param</code></strong></span> tag for each
allowable query argument. The format is</p><pre class="programlisting">
\@param <span class="emphasis"><em>parameter-name</em></span><span class="emphasis"><em>description...</em></span>
</pre>
</li><li class="listitem"><p>An <span class="strong"><strong><code class="computeroutput">\@author</code></strong></span> tag for each
author. Specify the author's name, followed his or her email
address in parentheses.</p></li><li class="listitem"><p>A <span class="strong"><strong><code class="computeroutput">\@creation-date</code></strong></span> tag
indicating when the script was first created.</p></li><li class="listitem"><p>A <span class="strong"><strong><code class="computeroutput">\@cvs-id</code></strong></span> tag containing the
page's CVS identification string. Just use <code class="computeroutput">$‌Id: tcl-documentation.html,v 1.2 2000/09/19
07:22:35 ron Exp $</code> when creating the file, and CVS will
substitute an appropriate string when you check the file in.</p></li>
</ul></div><p>These <code class="computeroutput">\@</code> tags are optional,
but highly recommended!</p>
</li>
</ul></div>
</div><div class="sect2">
<div class="titlepage"><div><div><h3 class="title">
<a name="tcl-doc-ad-library" id="tcl-doc-ad-library"></a>ad_library</h3></div></div></div><p>
<code class="computeroutput">ad_library</code> provides a
replacement for the informal documentation (described above) found
at the beginning of every Tcl page. Instead of:</p><pre class="programlisting">
# /packages/acs-kernel/00-proc-procs.tcl
#
# Routines for defining procedures and libraries of procedures (-procs.tcl files).
#
# jsalz\@mit.edu, 7 Jun 2000
#
# $‌Id: tcl-doc.xml,v 1.7.16.1 2023/07/10 08:36:09 gustafn Exp $
</pre><p>you'll now write:</p><pre class="programlisting">
# /packages/acs-kernel/00-proc-procs.tcl
ad_library {
Routines for defining procedures and libraries of procedures (<code>-procs.tcl</code>
files).
\@creation-date 7 Jun 2000
\@author Jon Salz (jsalz\@mit.edu)
\@cvs-id $‌Id$
}
</pre><p>Note that format is derived heavily from Javadoc: a general
description of the script's functionality, followed optionally
by a series of named attributes tagged by at symbols (<code class="computeroutput">\@</code>). HTML formatting is allowed. You are
encouraged to provide:</p><div class="itemizedlist"><ul class="itemizedlist" style="list-style-type: disc;">
<li class="listitem"><p>An <span class="strong"><strong><code class="computeroutput">\@author</code></strong></span> tag for each
author. Specify the author's name, followed his or her email
address in parentheses.</p></li><li class="listitem"><p>A <span class="strong"><strong><code class="computeroutput">\@creation-date</code></strong></span> tag
indicating when the script was first created.</p></li><li class="listitem"><p>A <span class="strong"><strong><code class="computeroutput">\@cvs-id</code></strong></span> tag containing the
page's CVS identification string. Just use <code class="computeroutput">$‌Id: tcl-documentation.html,v 1.2 2000/09/19
07:22:35 ron Exp $</code> when creating the file, and CVS will
substitute an appropriate string when you check the file in.</p></li>
</ul></div><div class="cvstag">($‌Id: tcl-doc.xml,v 1.7.16.1 2023/07/10
08:36:09 gustafn Exp $)</div>
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