Reference:Language Directives - Revision history

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2012-03-15T19:07:20Z

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[[Category:Language Directives]]
{{#indexentry:Directives, language|Language, directives}}
The POV Scene Language contains several statements called language directives which tell the file parser how to do its job. These directives can appear in almost any place in the scene file - even in the middle of some other statements. They are used to include other text files in the stream of commands, to declare identifiers, to define macros, conditional, or looped parsing and to control other important aspects of scene file processing.

Each directive begins with the hash character <code>#</code> (often called a number sign or pound sign). It is followed by a keyword and optionally other parameters.

In versions of POV-Ray prior to 3.0, the use of this <code>#</code> character was optional. Language directives could only be used between objects, camera or light_source statements and could not appear within those statements. The
exception was the <code> #include</code> which could appear anywhere. Now that all language directives can be used almost anywhere, the <code>#</code> character is mandatory. The following keywords introduce language directives.

<table summary="All language directives">
<tr valign="top">
<td width="25%">
<code>
[[Reference:Conditional Directives#The switch, case, range and break Directives|:#break|#break]] 
[[Reference:Conditional Directives#The switch, case, range and break Directives|:#case|#case]] 
[[Reference:User Message Directives#Text Message Streams|:#debug|#debug]] 
[[Reference:Declare and Local Directives|:#declare|#declare]] 
[[Reference:Default Directive|:#default|#default]] 
[[Reference:Conditional Directives#The if...else...end Directives|:#else|#else]] 
[[Reference:Conditional Directives#The if...else...end Directives|:#elseif|#elseif]] 
</code>
</td>
<td width="25%">
<code>
[[Reference:Conditional Directives#The if...else...end Directives|:#end|#end]] 
[[Reference:User Message Directives#Text Message Streams|:#error|#error]] 
[[Reference:File I/O Directives#The fclose Directive|:#fclose|#fclose]] 
[[Reference:File I/O Directives#The fopen Directive|:#fopen|#fopen]] 
[[Reference:Conditional Directives#The for Directive|:#for|#for]] 
[[Reference:Conditional Directives#The if...else...end Directives|:#if|#if]] 
[[Reference:Conditional Directives#The ifdef and ifndef Directives|:#ifdef|#ifdef]] 
</code>
</td>
<td width="25%">
<code>
[[Reference:Conditional Directives#The ifdef and ifndef Directives|:#ifndef|#ifndef]] 
[[Reference:Include Directive|:#include|#include]] 
[[Reference:Declare and Local Directives|:#local|#local]] 
[[Reference:User Defined Macros#The macro Directive|:#macro|#macro]] 
[[Reference:Conditional Directives#The switch, case, range and break Directives|:#range|#range]] 
[[Reference:File I/O Directives#The read Directive|:#read|#read]] 
[[Reference:User Message Directives#Text Message Streams|:#render|#render]] 
</code>
</td>
<td width="25%">
<code>
[[Reference:User Message Directives#Text Message Streams|:#statistics|#statistics]] 
[[Reference:Conditional Directives#The switch, case, range and break Directives|:#switch|#switch]] 
[[Reference:Declare and Local Directives#Destroying Identifiers with undef|:#undef|#undef]] 
[[Reference:Version Directive|:#version|#version]] 
[[Reference:User Message Directives#Text Message Streams|:#warning|#warning]] 
[[Reference:Conditional Directives#The while...end Directive|:#while|#while]] 
[[Reference:File I/O Directives#The write Directive|:#write|#write]] 
</code>
</td>
</tr>
</table>

Earlier versions of POV-Ray considered the keyword <code>#max_intersections</code> and the keyword <code>#max_trace_level</code> to be language directives but they have been moved to the <code>global_settings</code> statement and should be placed there without the <code>#</code> sign. Their use as a directive still works but it generates a warning and may be discontinued in the future.

@@ Line 6: / Line 6: @@
 <p>Each directive begins with the hash character <code>#</code> (often called a number sign or pound sign). It is followed by a keyword and optionally other parameters.</p>
-<p>In versions of POV-Ray prior to 3.0, the use of this <code>#</code> character was optional. Language directives could only be used between objects, camera or light_source statements and could not appear within those statements. The
+<p>In versions of POV-Ray prior to v3.0, the use of this <code>#</code> character was optional. Language directives could only be used between objects, camera or light_source statements and could not appear within those statements. The
 exception was the <code> #include</code> which could appear anywhere. Now that all language directives can be used almost anywhere, the <code>#</code> character is mandatory. The following keywords introduce language directives.</p>

@@ Line 1: / Line 1: @@
 [[Category:Language Directives]]
-{{#indexentry:Directives, language|Language, directives}}
+{{#indexentry:Directives, language}}
 <p>The POV Scene Language contains several statements called <em>language directives</em> which tell the file parser how to do its job. These directives can appear in almost any place in the scene file - even in the middle of some other statements. They are used to include other text files in the stream of commands, to declare identifiers, to define macros, conditional, or looped parsing and to control other important aspects of scene file processing.</p>

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