This was adapted from adamv@d5e78ee26535dec4b11c33d14832a9ee945a29fd

I decided prompting would was the most usable solution here, as the stem is
unlikely to be useful so the user would have to rename the file and change
the class name as well as type the command once and then again with --force.

Dissent welcome.

Fixes Homebrew/homebrew#15

We shouldn't mess with the user's PATH anyway. So assume our users are smart and just warn them about potential issues instead.

Our build directories are space-less, but the final destination may have
spaces, especially since OS X often uses your full name as your home directory
path.

I'm trying to only show the interesting stuff. You can see a full listing with
brew -v list, or by piping to other commands.

Tell me if you hate it or love it.

Otherwise you run the risk of not running the exact version / make of the utility you planned.

Fixes Homebrew/homebrew#48

Really we need to do this formula too, so I guess a make and cmake function are on the way…

References issue Homebrew/homebrew#48

Using more Pathname methods.

Only show text if verbose mode is on, as is typical for the rest of our install output.

TODO: would be nice if we knew you were a dev and automatically enabled verbose mode perhaps.

Allow Formula.skip_clean? to prevent empty folders from being removed
as part of the brewing cleanup process.

Is it a DSL? No. But people call it that apparently.

To add a dependency:

class Doe <Formula
  depends_on 'ray'
  depends_on 'mee' => :optional
  depends_on 'far' => :recommended
  depends_on Sew.new
end

Sew would be a formula you have defined in this Formula file. This is useful,
eg. see Python's formula. Formula specified in this fashion cannot be linked
into the HOMEBREW_PREFIX, they are considered private libraries. This allows
you to create custom installations that are very specific to your formula.

More features to come, like specifying versions

I left update_from_masterbrew! as a historical reference.

For this to work the "running script" must be the formulae file. Making this
so wasn't so hard, there is now an install.rb script which is included with
the -r flag to the ruby executable. An at_exit handler calls the install
function.

Having the install logic in its own file made it feel like there was so much
space that I added extra error handling. So there is something to be said for
separating functionality out into its own files.

Still the error handling sucks, we'll need to marshall the exception back to
the bin/brew command. Which is another PITA.

Still overall I think this will prove worthwhile. But if it doesn't we'll
revert.

As a first usage, you can put a diff after __END__ and return DATA from
Formula::patches to make Homebrew aware of it.

Renamed to Formula::class_s.

See comments in commit for details.

Specify dependencies in your formula's deps function. You can return an Array,
String or Hash, eg:

    def deps
      { :optional => 'libogg', :required => %w[flac sdl], :recommended => 'cmake' }
    end

Note currently the Hash is flattened and qualifications are ignored. If you
only return an Array or String, the qualification is assumed to be :required.

Other packaging systems have problems when it comes to packages requiring a
specific version of a package, or some patches that may not work well with
other software. With Homebrew we have some options:

1.  If the formula is vanilla but an older version we can cherry-pick the old
    version and install it in the Cellar in parallel, but just not symlink it
    into /usr/local while forcing the formula that depends on it to link to
    that one and not any other versions of it.
2.  If the dependency requires patches then we shouldn't install this for use
    by any other tools, (I guess this needs to be decided on a per-situation
    basis). It can be installed into the parent formula's prefix, and not
    symlinked into /usr/local. In this case the dependency's Formula
    derivation should be saved in the parent formula's file (check git or
    flac for an example of this).

Both the above can be done currently with hacks, so I'll flesh out a proper
way sometime this week.

I went with 0555 as the permissions changing only occurs to bin, sbin and lib, so there shouldn't be any files in there for editing in general anyway.

Formulae can specify not to "clean" any particular file by reimplementing the skip_clean? function, in case some config file or what not ends up in there.

Also committing cosmetic fix to pretty_duration function.

Discussion: d60fc4ba86d45255b0093303c45f6b1c2196fda2

We don't install documentation to save space. It seems pointless in this
modern age where the online docs are probably more up to date. However I do
believe this should be an option, defaulting to "don't install".

I confirmed this change with all relevant contributors first.

Signed-off-by: Max Howell <max@methylblue.com>

Automagically determines prefix to install to for DIY installations.

README amended.

Speeds up Python formula plenty in clean phase

Because we modified the ENV global each install this propagated to consecutive
formulae. So exec a new brew process each install. This is the safest way
although Ruby exceptions don't propagate to the parent process so I worry
about it somewhat.

Eg. man can be moved into share without consequences

Documentation is all online nowadays, and is more current there.

Documentation often takes up more space than the rest of the package.

Package listings are now more relevent.

We'll make it optional as soon as one person complains.

Large refactor to Formula, mostly improving reliability and error handling but
also layout and readability.

General improvements so testing can be more complete.

Patches are automatically downloaded and applied for Formula that return a
list of urls from Formula::patches.

Split out the brew command logic to facilitate testing.

Facility from Adam Vandenberg to allow selective cleaning of files, added
because Python doesn't work when stripped.