WHAT IS bras?

Bras is intended to do roughly the same job as the (in)famous
`make'-utitlity. It executes commands according to a set of rules.

Although I am quite happy with `make' most of the time, it has some
rough edges which I really dislike. Therefore I decided the other day
that I want to have my own little tool without the rough edges. The
result is bras.

Main features are:
o rule-controlled command execution, similar to make;
o written in Tcl, no compilation required;
o Tcl-syntax so that commands associated with rules may contain
  control structures;
o dependencies in foreign directories can trigger sourcing rule files
  in that directory, recursive bras-execution is not necessary;
o more than one type of rule: Newer, Exist, Always;
o new types of rules can be easily added;
o distinction between dependencies and mere prerequisites;
o multiple targets in one rule;
o multiple rules for a target;
o pattern rules which deserve the name;
   


An examples demonstrating the syntax is shown below. Note that
everything is Tcl.

########################################################################

## Prepare a list of source file names
set SRC {bla.c bli.c blu.c hello.c}

## Construct a list of object file names
regsub -all {\.c} $SRC .o OBJ

## Some variables needed for compilation
set CFLAGS "-g -Wall"
set LDLIBS "-L/opt/x11r6/lib -lX11"

## The next command declares a rule. It specifies that the command in
## braces has to be executed, whenever one of the files in $OBJ or the
## library ../xx/libxx.a is newer than target hello. Construction of
## the .o-files is handled by default rules. The `@' in front of the
## library path instructs bras to try to source ../xx/Brasfile, if
## available, and build libxx.a according to the rules specified there.

Newer hello "$OBJ @../xx/libxx.a {
  cc -o hello $OBJ -L../x -lxx $LDLIBS
}

## Installation usually depends on the existance of the target
## directory, while the time of update of the directory is irrelevant.
## The following rule specifies two thing:
##
## 1) The installed file $prefix/bin/hello must be newer than `hello'
## in the current directory. This includes the case where
## $prefix/bin/hello does not even exist. Then the cp-command must
## be executed.
##
## 2) However, the cp-command can only be executed if `$prefix/bin'
## exists. But the directory `$prefix/bin' is only a prerequisite,
## i.e. it must be up-to-date according to the rules, but its
## non-up-to-dateness cannot trigger the command.

Newer $prefix/bin/hello "hello // $prefix/bin" {
  cp hello $prefix/bin
}

## This rule now makes sure the installation directory exists. The
## list of dependencies // prerequisites is empty, but if necessary,
## one could put `$prefix' into the prerequisites part of the list.
Exist $prefix/bin {} {
  mkdir -p $prefix/bin
}
########################################################################
kir@iitb.fhg.de
$Revision: 1.4 $, $Date: 1997/07/26 09:53:56 $