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FUNNELWEB MANUAL WEB PAGE
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=========================
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Copyright (c) Ross N. Williams 1992,1999. All rights reserved.
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Permission is granted to redistribute and use this manual in
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any medium, with or without modification, provided that all
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notices (including, without limitation, the copyright
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notice, this permission notice, any record of modification,
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and all legal notices) are preserved on all copies, that all
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modifications are clearly marked, and that modified versions
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are not represented as the original version unless all the
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modifications since the manual's original release by Ross N.
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Williams (www.ross.net) consist of translations or other
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transformations that alter only the manual's form, not its
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content. THIS MANUAL IS PROVIDED "AS IS" AND WITHOUT ANY
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EXPRESS OR IMPLIED WARRANTIES, INCLUDING, WITHOUT
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LIMITATION, THE IMPLIED WARRANTIES OF MERCHANTIBILITY AND
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FITNESS FOR A PARTICULAR PURPOSE. TO THE EXTENT PERMITTED BY
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<TITLE>3.6 Comments</TITLE>
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<A HREF="index.html"><FONT COLOR="#FFFFFF"><B>Reference</B></FONT></A><BR>
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<A HREF="intro.html"><FONT COLOR="#FFFFFF">1 Introduction</FONT></A><BR>
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<A HREF="interface.html"><FONT COLOR="#FFFFFF">2 Interface</FONT></A><BR>
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<A HREF="scanner.html"><FONT COLOR="#FFFFFF">3 Scanner</FONT></A><BR>
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<A HREF="parser.html"><FONT COLOR="#FFFFFF">4 Parser</FONT></A><BR>
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<A HREF="analyser.html"><FONT COLOR="#FFFFFF">5 Analyser</FONT></A><BR>
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<A HREF="tangle.html"><FONT COLOR="#FFFFFF">6 Tangle</FONT></A><BR>
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<A HREF="weave.html"><FONT COLOR="#FFFFFF">7 Weave</FONT></A><BR>
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<A HREF="shell.html"><FONT COLOR="#FFFFFF">8 Shell</FONT></A><BR>
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<A HREF="commands.html"><FONT COLOR="#FFFFFF">9 Commands</FONT></A><BR>
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<A HREF="glossary.html"><FONT COLOR="#FFFFFF">10 Glossary</FONT></A><BR>
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<A HREF="references.html"><FONT COLOR="#FFFFFF">11 References</FONT></A><BR>
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<P><FONT SIZE="5">3.6 Comments</FONT><BR>
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<P>When FunnelWeb encounters the <SAMP>@!</SAMP>
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sequence during its left-to-right scan of the line, it
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throws away the rest of the line (including the EOL) without
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analysing it further. Comments can appear in any line except
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"<TT>@i</TT>", "<TT>@t</TT>", and "<TT>@p</TT>" lines.
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<P>FunnelWeb comments can be used to insert comments into
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your input file that will neither appear in the product
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files nor in the documentation file, but will be solely for
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the benefit of those reading and editing the input file
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@! I have used a quick macro for this definition
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@! as it will be used often.
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<P>Because comments are defined to include the end-of-line
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marker, care must be taken when they are being added or
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removed within the text of macro bodies. For example the
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for (i=0;i<MAXVAL;i++) @! Print out a[0..MAXVAL-1].
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for (i=0;i<MAXVAL;i++) printf("%u\n",a[i]);
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<P>This problem really has no solution; if FunnelWeb
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comments were defined to omit the end of line marker, the
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expanded text would contain trailing blanks! As it is,
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FunnelWeb comments are designed to support single line
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comments which can be inserted and removed as a line without
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causing trouble. For example:
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@! Print out a[0..MAXVAL-1].
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for (i=0;i<MAXVAL;i++)
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<P>If you want a comment construct that does not enclose
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the end of line marker, combine the insert end of line
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construct <SAMP>@+</SAMP> with the comment construct
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<SAMP>@!</SAMP> as in
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for (i=0;i<MAXVAL;i++) @+@! Print out a[0..MAXVAL-1].
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<P>FunnelWeb comments should really only be used to
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comment the FunnelWeb constructs being used in the input
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file. Comments on the target code are best placed in
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comments in the target language or in the documenting text
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surrounding the macro definitions. In the example above, a C
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comment would have been more appropriate.
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<A HREF="copyright.html">Copyright © Ross N. Williams 1992,1999. All rights reserved.</A><BR>
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