Proposed changes for pass 1 wml_p1_ipp

[Franz Knipp <nospam@thanx>]

Hello,

while experimenting with pass 1 I found a strange behaviour in handling
the comments - #include and variable substitution was done also their...

Furthermore, I'd some ideas to improve the new #include tag.

I've attached a diff -u ;-) to the original
wml-1.7.4/wml_backend/p1_ipp/ipp.src.

Use it:

$ patch ipp.src diff.ipp.src

The changes:

I'll start with the good ones:

*  If you include files with the #include 'pattern' tag, there are three
variables which are set to the complete file name (with path and
extension) of itself, the previous and the next file: INCLUDE_SRC,
INCLUDE_PREV, INCLUDE_NEXT. These variables are available with e. g.
$(INCLUDE_SRC). If you want to use them in the further passes, you have to
assign variables like <set-var INCLUDE_SRC=$(INCLUDE_SRC).

*  Comment blocks are now really comment blocks, that means that no
#include, #use, #depend, variable substition and so on is performed on
that block. This is true for # line comments and /* */ C-style comments.

*  The handling of comments is now done in another part and should be
faster than previos (therefore I deleted the warning in the man page).

*  Silent Assign Methods: to assign variables without writing themselves
to the output (file) I've invented the following "variable substitutions":

   $(name:!value)  Silent Assign: name = value, also if name is yet
                     definied

   $(name:~value)  Silent Assign when Unset

And now, the bad news:

*  Because C-style comments are handled in another way now, they cannot
longer be nested. With this patch wml behaves like the standard cpp.

*  Another caveat is therefore the handling of /* which you'll find often
as dirname/*.ext. In the #include, #use and #depend directives you don't
have to care about it, you should not use comments there (comments which
start and end at this line are deleted properly, but you must not mix them 
with something like dirname/*.ext, this could fail). In the rest
of the file (except it is protected against pass 1) you've to escape them
with a leading backslash like \/* and \*/. After pass 1 you'll find there
a nice /* and */.

*  Keep in mind that the #include directives are not longer executed in a
C-style comment block (I think that's more logic than executing them).

I think, these disadvantages will concern only a few sites... (I hope
none). The real critical point is the handling of existing `/*' if they're
unprotected against pass 1. But a simple 

$ grep -r "/\*" *

will show, if you are using them in one of your files. You will have to
escape them only if they're not on an #include, #use or #depend line.

I hope you'll find the errors in my source, maybe my solution is not that
practicable as I think.

To Denis (I think this is your first name): I've updated the documentation
part ;-) That's necessary for me to keep in mind my changes ;-))

To Carsten: may I make a link to your page on my wml page?

To all who don't know yet: after applying the patch you only have to

$ make && make install-core

in the wml-1.7.4 directory (faster than a full install).

Greetings, 

Franz

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Franz KNIPP                                               +34 65 44 26 555 
C/ Poeta Ricard Sanmarti, 4-10                            E-46020 Valencia
http://www.knipp.org/franz/                                franz@knipp.org
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diff.ipp.src