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<HEAD>
<TITLE>2.3 Indentation</TITLE>
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<A HREF="intro.html"><FONT COLOR="#FFFFFF">1 Introduction</FONT></A><BR>
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<P><FONT SIZE="5">2.3 Indentation</FONT><BR>
<P>The body of the <SAMP>print</SAMP> macro of the previous
example contains two lines of text. A literal substitution
of this macro's body in its context would result in:
<P>
<PRE>
{
printf("Hello World!");
printf("\n");
printf("Hello World!");
printf("\n");
}
</PRE>
<P>But instead, it comes out as (have a look at this part
of <SAMP>hello.c</SAMP> now):
<P>
<PRE>
{
printf("Hello World!");
printf("\n");
printf("Hello World!");
printf("\n");
}
</PRE>
<P>The explanation is that FunnelWeb indents each line of
multiline macros by the level of indentation at the point of
call. This means that, as in the case above, program texts,
which are usually highly indented, come out looking
"right".
<P>In other circumstances, where the model of the text is
one dimensional, FunnelWeb's indentation could become an
impediment or even a danger. In these cases, it can be
switched off by including the FunnelWeb
<STRONG>pragma</STRONG> line
<P>
<PRE>
@p indentation = none
</PRE>
<P>anywhere in the input file.
<P>One of the design goals of FunnelWeb is to allow the
user total control over the product files. This contrasts
with the approach of Knuth's WEB system
<STRONG>[Knuth83]</STRONG> (upon which FunnelWeb is based), which
mangles the input text at the Pascal program
syntax level, truncating identifiers, converting the text to
upper case, and paragraphing text. Here is an example of
part of a Pascal program produced by
WEB (from page 14 of
<STRONG>[Knuth83]</STRONG>):
<P>
<PRE>
IF R=0 THEN XREF[P]:=XREFPTR ELSE
XMEM[R].XLINKFIELD:=XREFPTR;END;{:51}
{58:}FUNCTION IDLOOKUP(T:EIGHTBITS):NAMEPOINTER;
LABEL 31;
VAR I:0..LONGBUFSIZE;H:0..HASHSIZE;K:0..MAXBYTES;
W:0..1;
L:0..LONGBUFSIZE;P:NAMEPOINTER;BEGIN
L:=IDLOC-IDFIRST;{59:}
H:=BUFFER[IDFIRST];I=IDFIRST+1;
WHILE I<IDLOC DO BEGIN H:=(H+H+BUFFER[I])MOD
HASHSIZE;I=I+1;END{:59};
</PRE>
<P>Knuth's theory is that the program generated by a
literate programming system should be treated as object code
and hence should look like object code too. While this may be an admirable approach in the long
run, the present programming environment is one of faulty
compilers and buggy tools. The FunnelWeb view is that, in
this environment, the programmer needs all the help he can
get and that therefore he should be allowed total control
over the product file. Another reason for FunnelWeb's
providing total control over the product file, is that
FunnelWeb is intended to be target language independent, and
so even if Knuth's view were adopted, it would not be clear
what a legitimate transformation of the text could be.
<P>
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