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<P><FONT SIZE="5">4.14 Macros Are Static</FONT><BR>
<P>In FunnelWeb, the actions of <I>macro definition</I>
and <I>macro expansion</I> occur during two separate
phases (parser and tangle) and cannot be interleaved. As a
result, the FunnelWeb macro facility is completely static.
It is not possible for one macro to define another while the
first macro is being expanded; each must be defined
statically. It is not possible to define a macro to even
assist in the definition of other macros. Because the
scanner, parser, analyser, and tangler phases are all
invoked sequentially, there is no room for feedback of
definitions between different levels (e.g. the user cannot
define a macro for the <SAMP>vskip</SAMP> pragma).
<P>This lack of power is fully intentional. By totally
excluding the more incomprehensible ways in which a general
purpose macro preprocessor can be used, FunnelWeb provides
definite guarantees to the reader of its input files:
<P>
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<LI> FunnelWeb guarantees that a piece of text does not
contain a macro call unless it contains the special
character followed by <SAMP><</SAMP> or <SAMP>#</SAMP>.
<LI> FunnelWeb allows calls to be made to macros that are
defined later in the input file.
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