bras
Rule Based Command Execution

Current Version is 2.3.2. Download most recent: bras-2.3.2.tar.gz CHANGES Documentation manual: (pdf) (ps) command line:bras.1 older versions Hosted by

What is it? Bras helps to keep files, or targets, up-to-date with respect to a set of dependencies. For every target, a rule describes what it means for the target to be out-of-date and what has to be done to refresh it.

Why not make? While make is probably the application most often used in *nix software development, I guess everyone who has written makefiles would agree that make has a few very odd features. My personal "favorite" misfeatures of make are: ugly mix of shell-syntax with makes own syntax, confusing way to expand macros and incomplete handling of dependence relations spanning multiple directories (see Peter Miller's Recursive Make Considered Harmful).

Features

up-to-date'ness

Conditions which test whether a target is out-of-date with respect to its dependencies can be freely defined; currently implemented tests include older, md5older, updated.

multiple directories

Bras can follow targets into other directories. It acts there according to the local brasfile to update the target and then reports the result back. Because no recursive execution of bras is necessary, the result of the reasoning for that other directory is not lost.

non-file targets

Targets need not be files. In fact a target is just a name. It depends on the rules formulated for the target of how that name is used.

pattern rules

Pattern rules automatically derive dependencies and thereby patterns via freely definable functions. Make's suffix rules are implemented as a trivial special case.

consistent syntax

Bras is implemented in Tcl. Rules can be mixed with procedural parts. In particular control structures can be used to automatically collect lists of targets, find out platform specifics or selectively activate rules.

module

While bras is normally started on the command line, the whole rule evaluation functionality is available as a Tcl module and can even be used in a GUI-based application implemented in Tcl/Tk.

One very tiny example

The best way to get an idea of how bras works is to download the distribution and look at some of the files in the examples subdirectory. Nevertheless I'll give a three liner here:

   set SRC [glob *.c] 
   Make hello {[older hello $SRC]} {
     cc -o hello $SRC
   }

The first line collects all .c-files in the current directory. The 2nd line says that to make target hello bras must test if that file is older than any in list just collected. If it is the case, the compiler is started to update hello.

Please send comments and suggestions to Harald Kirsch.