Release of CWEBx3.0, another implementation of CWEB
===================================================

After several versions with beta status, CWEBx is now officially released as
version CWEBx3.0. The system is available at

			ftp://ftp.cwi.nl/pub/cweb

and will hopefully also be available soon at the Literate Programming Archive
(ftp://ftp.th-darmstadt.de/pub/programming/literate-programming/c.c++) and
at the CTAN sites. An earlier version was released last year under the name
`CWEB 3.x'. With respect to that version the main changes are improved
compatibility with Levy/Knuth CWEB, and greater reliability. All extras that
were added in Levy/Knuth CWEB have been incorporated, and a compatibility
mode is added in which the external behaviour of Levy/Knuth CWEB is
simulated exactly. The main version number `3' now indicates compatibility
with the corresponding major version of Levy/Knuth CWEB, which was not the
case for CWEB 3.x. (The minor version numbers of Levy/Knuth CWEB only involve
bug fixes that are usually not relevant to CWEBx; all bugs that are repaired
in Levy/Knuth CWEB 3.3, and many that are not, are absent in CWEBx3.0). A
few new features have also been added, mainly to increase flexibility of use.

As a reminder, here is a summary of the new aspects that were already
present in CWEB 3.x.

- The effect of typedef declarations on formatting extends over the complete
  source text, rather then starting at the declaration itself.
- A control code for inclusion of header files, which causes any typedef
  declarations in the header file to be taken into account in formatting.
- A mechanism for referring to section numbers using symbolic labels.
- A control code to start a section without allowing a page break.
- A control code to denote the bitwise-or operator `|' within `|...|'.
- A control code to force a negative indentation by one unit on a line.
- The size of an indentation can be controlled by a parameter.
- A defaulting mechanism on command line to use change file if it is present.
- CTANGLE matches parentheses and braces in macros and modules bodies.
- Several layout styles may be selected from the command line.
- Irreducible scrap sequences can be shown without changing the source files.
- Automatic breaking of long expressions using precedence rules.
- New and modular set of grammar rules, based directly on the ANSI C syntax.
- Syntax category of module names can be controlled; default is statement.
- A completely new manual, with a one-page table of all control codes.

- CWEB programs are system independent, no change files needed.
- Organisation of programs is much more C-like, using ordinary header files
  for communication between compilation units.
- Documentation of source code is improved, programs are more literate.

The following features are the main additions made since CWEB 3.x

- Control codes @s, @q, @l, @h, from Levy/Knuth CWEB.
- Relaxation of the rules, e.g. for module names, as in Levy/Knuth CWEB.
- Compatibility mode with Levy/Knuth CWEB.
- Possibility to send index and module names to separate files.
- Possibility to get human-oriented output from CTANGLE, omitting #line,
  but retaining comments and indentation.
- Possibility to specify search path for header files on command line.
- Possibility to indicate that a typedef identifier is used as an ordinary
  one, e.g., as a field in a structure.
- Possibility to treat short compound statments as simple ones in formatting.
- An improved and even more complete manual (now 32 pages).

Marc van Leeuwen
CWI, Amsterdam