"Smkfile" format

Overview

A Smkfile is a simple text file, containing commands.

Here is a simple first exemple of Smkfile: 

gcc -o hello.o -c hello.c
gcc -o main.o -c main.c
gcc -o hello hello.o main.o

Smkfile is named after Makefile exemple.
Both term will be used hereafter to avoid any ambiguity regarding the intended file format.

As the project goal is to greatly simplify the make process, the Smkfile format is logically much simpler, and thus not fully compatible with the Makefile format.

As an illustration, consider the functionnaly equivalent Makefile of the previous exemple of Smkfile: 

hello.o: hello.c
    gcc -o hello.o -c hello.c

main.o: main.c hello.h
    gcc -o main.o -c main.c

hello: hello.o main.o
    gcc -o hello hello.o main.o

A lot more verbose, isn't it?

The good news is that Smk can run both file in the same way, so that to avoid rewriting (simple) existing Makefiles.

More generally speaking, a Smkfile may contains:

(Blank lines are ignored).

Comments

Smk recognize several comments formats (but single line comments only), so keep your own habit :

  • the Ada way, that is starting with --,
  • the Java / C# way, starting with //,
  • the Shell and Make way, starting with #.

(Those format seems to be the most popular for single line comments in programming languages, according to Rosetta Code)

Comments following a command are not removed, and will be passed to the shell during the spawn :

# this comment will be ignored 
gcc -o hello.o -c hello.c # this comment will be passed to gcc!

Note that this format is compatible with Shebang notation, so your Smkfile may perfectly be a shell script like this :

#!/bin/bash

gcc -o hello.o -c hello.c
gcc -o main.o -c main.c
gcc -o hello hello.o main.o

Sections

Sections are labels in the file that specificaly designate the following commands (until next section). It allows for exemple to run only the clean section of a Makefile. Fixme: Not yet implemented, as of v0.0.4
Refer to the Compatibility with Makefile chapter.

Commands

A command line is whatever line that is neither a blank, Section or Comment line. Once removed heading blanks, tabs and '@' characters, the rest of the line passed 'as is' to the shell to be run. Shell or Make variables, pattern rules, constructs, etc. are not interpreted. So, don't expect $(MAKE), %.d: %.c, if [ $1 -gt 100 ], etc. to have the right behavior.

Compatibility with Makefile

A makefile consists of “rules” in the following form:

target: dependencies
    system command(s)

  1. Makefile command lines start with a tab, and that's OK for Smk. A line may also starts with '@' (in that case, Make suppress the echoing of that line).
    Like Make, Smk discards the '@' character before the line is passed to the shell (but smk will not suppress the echoing).

  2. Dependencies are determined automatically by Smk so dependencies following target: are ignored.

  3. Targets are also determined automatically by Smk, but the target also plays another role in Makefile, like in this exemple: 

all: hello

hello: hello.o main.o
    gcc -o hello hello.o main.o

clean:
    rm -rf *.o

mrproper: clean
    rm -rf hello

A user calling make don't expect mrproper to be run immediatly after the build. As of version v0.0.2, this is the behavior of Smk : all lines are run if needed sequentially, forcing the user to split incompatible sequences of commands in several files (for exemple here build.txt, clean.txt and mrproper.txt).

To avoid this burden, Smk will provide in future version the hability to run only the commands following the target. To avoid confusion with targets in the more general meaning, identifier followed by colon (':') will be called Section instead.

In this exemple: 

build: 
    gcc -o hello hello.o main.o

build is the section name, hello is the target, and both .o (and possibly included .h) are the sources.

  1. Makefile targets may also be invoked to ask for a particular intermediate production.

For exemple, in: 

hello: hello.o main.o
    gcc -o hello hello.o main.o

hello.o: hello.c
    gcc -o hello.o -c hello.c

main.o: main.c hello.h
    gcc -o main.o -c main.c

One could invoke make hello.o.

But in Smkfile, targets are not explicitly stated.
This is why smk provides way to:

  • Ask for the possible target list:
    smk --list-targets Makefile (or smk -lt Makefile)

  • Build specifically whatever file from the listed target:
    smk hello.o
    Fixme: Not yet implemented, as of v0.0.4

  • Multilines (splitted with backslash) are processed.