The array elements here are individual arguments to exec, not a string
to pass to the shell; this only appeared to work. In reality, `opam
list` accepts "|" as valid argument, and the command works fine without
grepping the output.
New `depends_on :python` Dependency.
New `depends_on :python3` Dependency.
To avoid having multiple formulae with endings -py2 and -py3,
we will handle support for different pythons (2.x vs. 3.x)
in the same formula.
Further brewed vs. external python will be transparently supported.
The formula also gets a new object `python`, which is false if
no Python is available or the user has disabled it. Otherwise
it is defined and provides several support methods:
python.site_packages # the site-packages in the formula's Cellar
python.global_site_packages
python.binary # the full path to the python binary
python.prefix
python.version
python.version.major
python.version.minor
python.xy # => e.g. "python2.7"
python.incdir # includes of python
python.libdir # the python dylib library
python.pkg_config_path # used internally by brew
python.from_osx?
python.framework?
python.universal?
python.pypy?
python.standard_caveats # Text to set PYTHONPATH for python.from_osx?
python.if3then3 # => "" for 2.x and to "3" for 3.x.
Further, to avoid code duplication, `python` takes an optional
block that is run twice if the formula defines depends_on
:python AND :python3.
python do
system python, 'setup.py', "--prefix=#{prefix}"
end
Read more in the Homebrew wiki.
By always passing around a single, unnested array rather than splatting
and then defensively flattening and compacting things, we can avoid
allocating a bunch of unnecessary arrays. This gives a performance boost
of roughly 4% when enumerating 2500 formulae, and has the side effect of
cleaning up the dependency API.
