add help target to scons build

Replying to jsd:

i'd like to see a help target for scons, e.g. % scons help following targets are supported whatever - default target tests - compile and run tests clean - same as scons -c help - this screen

I don't now about targets, but with scons --help you at least get the options.

this makes it for us old people used to make a bit more comprehensible also new capabilities in the build system (experessed in build targets) are more easily detected. oh, the clean target i would really like to see.

I haven't tried it, but scons should be able to do a clean out of the box with scons --clean.

Replying to cneumann:

I don't now about targets, but with scons --help you at least get the options.

…which are used for most of these things. Which I'm not too excited about, I liked the old make-style targets better. But then I'm an old fart, so I'm trying to be more modern.

I haven't tried it, but scons should be able to do a clean out of the box with scons --clean.

Yup. The alternative is just removing the build directory. The next build will recreate everything.

The main problem is that scons doesn't have targets the way make does. Every file is a target (like make), and you can add Aliases to have simpler names (e.g. I just added Aliases for the individual libraries as I didn't want to rebuild the whole system to just run Base tests). But those are just conveniences, not first-class objects like in make.

It would probably make sense to have additional documentation for aliases, and for the old people it might make sense to have a help target.