1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
|
<HTML>
<!--
***********************************************************************
FUNNELWEB MANUAL WEB PAGE
=========================
Copyright (c) Ross N. Williams 1992,1999. All rights reserved.
Permission is granted to redistribute and use this manual in
any medium, with or without modification, provided that all
notices (including, without limitation, the copyright
notice, this permission notice, any record of modification,
and all legal notices) are preserved on all copies, that all
modifications are clearly marked, and that modified versions
are not represented as the original version unless all the
modifications since the manual's original release by Ross N.
Williams (www.ross.net) consist of translations or other
transformations that alter only the manual's form, not its
content. THIS MANUAL IS PROVIDED "AS IS" AND WITHOUT ANY
EXPRESS OR IMPLIED WARRANTIES, INCLUDING, WITHOUT
LIMITATION, THE IMPLIED WARRANTIES OF MERCHANTIBILITY AND
FITNESS FOR A PARTICULAR PURPOSE. TO THE EXTENT PERMITTED BY
LAW THERE IS ABSOLUTELY NO WARRANTY.
***********************************************************************
-->
<HEAD>
<TITLE>2.1 Simple Macros</TITLE>
<STYLE TYPE="text/css"> <!-- A {text-decoration: none} // --> </STYLE>
</HEAD>
<BODY BACKGROUND="binary/background.gif"
BGCOLOR="#FFFFFF"
TEXT="#000000"
VLINK="#660000"
LINK="#FF0000"
ALINK="#CC0000">
<TABLE WIDTH="490">
<TR>
<TD WIDTH="130" VALIGN="top">
<IMG SRC="binary/d_clear.gif" ALT="" WIDTH="130" HEIGHT="1"><BR>
<FONT SIZE="2">
<BR>
<A HREF="http://www.ross.net/"
TARGET="rosshome"
onClick="window.open('','rosshome','location,status,menubar,scrollbars,resizable',false).focus(); return true;"
>
<IMG SRC="binary/rossnet_logo.gif"
WIDTH="64" HEIGHT="32"
BORDER="0" ALT="RossNet"
HSPACE="0" VSPACE="1"></A><BR>
<BR>
<A HREF="../index.shtml"
TARGET="funnelweb"
onClick="window.open('','funnelweb','location,status,menubar,scrollbars,resizable',false).focus(); return true;"
>
<IMG SRC="binary/linklogo.gif"
WIDTH="64" HEIGHT="32"
BORDER="0" ALT="FunnelWeb"
HSPACE="0" VSPACE="1"></A><BR>
<BR>
<TABLE CELLSPACING=0 CELLPADDING=0 BORDER=0><TR><TD BGCOLOR="#000000">
<A HREF="../reference/index.html"
TARGET="funnelwebreference"
onClick="window.open('','funnelwebreference','location,status,menubar,scrollbars,resizable',false).focus(); return true;"
><FONT COLOR="#FFFFFF"><B>Reference</B></FONT></A><BR>
<BR>
<A HREF="../developer/index.html"
TARGET="funnelwebdeveloper"
onClick="window.open('','funnelwebdeveloper','location,status,menubar,scrollbars,resizable',false).focus(); return true;"
><FONT COLOR="#FFFFFF"><B>Developer</B></FONT></A><BR>
<BR>
<A HREF="index.html"><FONT COLOR="#FFFFFF"><B>Tutorial</B></FONT></A><BR>
<A HREF="intro.html"><FONT COLOR="#FFFFFF">1 Introduction</FONT></A><BR>
<A HREF="macro.html"><FONT COLOR="#FFFFFF">2 Macros</FONT></A><BR>
<A HREF="type.html"><FONT COLOR="#FFFFFF">3 Typesetting</FONT></A><BR>
<A HREF="example.html"><FONT COLOR="#FFFFFF">4 Example</FONT></A><BR>
<A HREF="hints.html"><FONT COLOR="#FFFFFF">5 Hints</FONT></A><BR>
<A HREF="examples.html"><FONT COLOR="#FFFFFF">6 Examples</FONT></A><BR>
<A HREF="web.html"><FONT COLOR="#FFFFFF">7 Webmaking</FONT></A><BR>
<BR>
<A HREF="search.html"><FONT COLOR="#FFFFFF"><B>SEARCH</B></FONT></A><BR>
</FONT>
</TD></TR></TABLE>
</TD>
<TD WIDTH="360" VALIGN="top">
<FONT SIZE="3">
<A HREF="../reference/index.html"><IMG SRC="binary/title.gif"
WIDTH="302" HEIGHT="24"
BORDER="0" ALT="FunnelWeb Tutorial Manual"
HSPACE="0" VSPACE="0"></A>
<P><FONT SIZE="5">2.1 Simple Macros</FONT><BR>
<P>The original "Hello World" program consisted of
a single macro definition.
<P>
<PRE>
@O@<hello.txt@>@{Hello World@+@}
</PRE>
<P>In fact, this is a rather exceptional macro, as it
causes its expansion to be written to a product file. The
<SAMP>@O</SAMP> (for <STRONG>O</STRONG>utput) signals this. In
FunnelWeb, most macros are defined using
<SAMP>@$</SAMP>. This results in a macro
that does not generate a product file, but which can be
called in other macros (including <SAMP>@O</SAMP> macros). Let
us expand the hello world program to include some other
macros.
<P>
<PRE>
@O@<hello.txt@>@{@<Greetings@>@+@}
@$@<H@>==@{Hello@}
@$@<W@>==@{World@}
@$@<Greetings@>==@{@<H@> @<W@>@}
</PRE>
<P>Type in the file and run it through FunnelWeb using the command:
<P>
<PRE>
fw hello
</PRE>
<P>The product file (result.out) should look like this:
<P>
<PRE>
Hello World
</PRE>
<P>This short program illustrates some of the features of
ordinary macros in FunnelWeb. Consider the <SAMP>@O</SAMP>
macro. Instead of containing straight text ("Hello
World"), it now contains the macro call
<SAMP>@<Greetings@></SAMP>. A FunnelWeb macro can
be called from within the body of another macro just by
giving the macro name delimited in <SAMP>@<</SAMP> and
<SAMP>@></SAMP>.
<P>At the bottom of the file is the definition of the
<SAMP>@<Greetings@></SAMP> macro. The definition
is similar to the definition of <SAMP>hello.txt</SAMP> except
that it starts with <SAMP>@$</SAMP> to indicate that no
product file is desired from this macro (directly). It also
employs the optional <SAMP>==</SAMP> syntax which has no
semantic impact, but can be used to make definitions
clearer. The body of the
<SAMP>@<Greetings@></SAMP> macro consists of
calls to the <SAMP>H</SAMP> and <SAMP>W</SAMP> macros which are
defined immediately above.
<P>Note that the macros are not constrained to be defined
in any particular order. One of the main features of
literate programming tools is that they allow the different
parts of the text document being developed (usually a
computer program) to be layed out in any
order. So
long as there is a definition somewhere in the input file
for every macro call, FunnelWeb will sort it all out.
<P>In fact, FunnelWeb's macro facility is very
simple. Unlike many macro
preprocessors which allow macros to define other macros,
FunnelWeb completely finishes parsing and analysing the
macros in the input file before it starts expanding them
into product files. Other preprocessors allow macros to be
redefined like variables (as in, say, TeX)
taking on many different values as the macro pre-processor
travels through the input file. In contrast, FunnelWeb has
no concept of "different times" and treats the input
as one huge static orderless, timeless, collection of
definitions. In FunnelWeb, there is only ever one time, and
so there can only ever be one value/definition for each
macro.
<P>
<TABLE WIDTH="100%">
<TR>
<TD ALIGN="left" VALIGN="bottom"><A HREF="macro.html"><IMG SRC="binary/fw_left.gif" HEIGHT="32" WIDTH="32" BORDER="0" ALT="Prev"></A></TD>
<TD ALIGN="center" VALIGN="bottom"><A HREF="macro.html"><IMG SRC="binary/fw_up.gif" HEIGHT="32" WIDTH="32" BORDER="0" ALT="Up"></A></TD>
<TD ALIGN="right" VALIGN="bottom"><A HREF="macro_times.html"><IMG SRC="binary/fw_right.gif" HEIGHT="32" WIDTH="32" BORDER="0" ALT="Next"></A></TD>
</TR>
</TABLE>
<HR>
<FONT SIZE="2">
<A HREF="mailto:webmaster@ross.net">Webmaster</A>
<A HREF="copyright.html">Copyright © Ross N. Williams 1992,1999. All rights reserved.</A><BR>
</FONT>
</FONT>
</TD>
</TR>
</TABLE>
</BODY>
<!-- *********************************************************************** -->
<!-- End Of A FunnelWeb Manual Web Page (www.ross.net/funnelweb/) -->
<!-- *********************************************************************** -->
</HTML>
|
