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<title>ploticus: script syntax changes - version 2.00</title>
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<td><br><h2>Script syntax changes - version 2.00</h2></td>
<td align=right>
<small>
<a href="../doc/Welcome.html"><img src="../doc/ploticus.gif" border=0></a><br>
<a href="../doc/Welcome.html">Welcome</a>
<a href="../gallery/index.html">Gallery</a>
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<title>Manual page for Script_syntax_changes_-_version_2.00(PL)</title>
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<body>
<h2>NEW SCRIPT INTERPRETER</h2>
Ploticus release 2.00 debuts a new underlying script interpreter system,
with some consequent changes in legal script syntax.<tt> </tt>
These changes should be fairly obscure; when I tested on the collection of
gallery examples there were minor problems with 3 or 4 of the examples and these were easily fixed.<tt> </tt>
I appologize in advance for any disruption this may cause.<tt> </tt>
<p>
The following is a summary
of known changes; if you find others, please inform me
(<tt>scg@jax.org</tt>).<tt> </tt>
<p>
<b>Changes that may require maintenance to existing scripts:</b>
<ul>
<li>
Variables no longer need to be <b>#declare</b>d.<tt> </tt>
<b>#declare</b> no longer does anything; if encountered
it will be silently ignored.
Scripts that depended on <b>#declare</b> to initialize a
variable should now use <b>#set</b> or <b>#setifnotgiven</b> instead.<tt> </tt>
<br>
<br>
<li>
<b>#setifnotgiven</b> should be used to set a default value for any
variable that may be passed in to the script. Scripts that use
<b>#declare soft</b>, <b>$exists()</b>, or <b>$notexists()</b> to
handle passed variables should be changed to use <b>#setifnotgiven</b>.<tt> </tt>
<br>
<br>
<li>
References to variables that have never been given a value
cause evaluation to be cancelled, leaving the variable name to appear
in result, and do not cause an error message to be issued.
<br>
<br>
<li>
Concatenation of constants and/or variables in <b>#set</b> statements
are now done differently. You used to be able to do this:
<tt>#set A = /home/scg/data/@TESTRUN </tt>
<br>
Now it must be done this way:
<tt>#set A = "/home/scg/data/" @TESTRUN</tt>
<br>
<br>
<li>
Implicit concatentation of constants and/or variables in an <b>#if</b> statement
is longer supported. For instance, you used to be able to do this:
<br>
<tt>#if @FILENAME = /home/scg/data/@TESTRUN</tt>
<br>
Now it must be done this way:
<pre>
#set F = "/home/scg/data/" @TESTRUN
#if @FILENAME = @F
...
</pre>
<li>
<b>#clone</b> no longer accepts a filename argument.
Use <b>#include</b> and <b>#procdef</b> instead.<tt> </tt>
<br>
<br>
<li>
The <b>$change()</b> function no longer supports the special symbol <tt>space</tt>.<tt> </tt>
A space may be represented naturally, eg <tt>$change( "_", " ", @FOO )</tt>
<br>
<br>
<li>
The <b>$validate()</b> function is no longer supported.<tt> </tt>
Scripts should use $isnumber() to test numbers,
$datevalid() to test date values,
and $timevalid() to test time values.<tt> </tt>
<br>
<br>
<li>
Trailing comments may cause errors where they didn't before.<tt> </tt>
This line contains a trailing comment:
<pre>
rectangle: 1 1 5 6.5 //xlo, ylo, xhi, yhi
</pre>
The documentation has always stated that "any line beginning with a double slash (//)
is taken as a comment", however some of the examples may have used trailing
comments. When in doubt don't use them. <i>(added Oct 2 '01)</i>
<br><br><br>
</ul>
<p>
<b>Changes that should not affect existing scripts:</b>
<ul>
<li>
<b>#if</b> statements support quoted operands,
useful for constants that have embedded white space.<tt> </tt>
Example: <tt>#if @A = "hello world"</tt>
<br>
<br>
<li>
Function constructs may now contain embedded spaces, and quoted arguments.<tt> </tt>
Exceptions are <b>$arith()</b> and <b>$arithl()</b>, which do not allow
embedded spaces within the arithmetic expression.<tt> </tt>
<br>
<br>
<li>
<b>#hideund</b> and <b>#showund</b> directives are no longer necessary,
and are silently ignored.<tt> </tt>
<br>
<br>
</td></tr>
<td align=right>
<a href="../doc/Welcome.html">
<img src="../doc/ploticus.gif" border=0></a><br><small>data display engine <br>
<a href="../doc/Copyright.html">Copyright Steve Grubb</a>
<br>
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<center>
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