Automatic ASSUME_PROVIDED based upon what's available in the build machine (not for the faint of heart, you've been warned)

__init__.py

assume.bbclass

def auto_assume_provided():
    import kergoth.assume as assume
    import kergoth.assumptions

    return ' '.join(assume.test_assumptions())

ASSUME_PROVIDED += "${@auto_assume_provided()}"

assume.py

import os


assumptions = {}


def have(cmd):
    for subdir in os.environ.get('PATH', '').split(':'):
        if os.path.exists(os.path.join(subdir, cmd)):
            return True
    return False

def simple_assumptions(check, *cmds, **kwcmds):
    def check_assumption(cmd, provide):
        if check(cmd):
            return provide

    def new_check_assumption(provide):
        return lambda cmd: check_assumption(cmd, provide)

    native_check = lambda cmd: check_assumption(cmd, '%s-native' % cmd)
    for cmd in cmds:
        assumptions[cmd] = native_check

    for cmd, provide in kwcmds.iteritems():
        assumptions[cmd] = new_check_assumption(provide)

call = lambda x: x()
def assumed(func):
    assumptions[func] = call
    return func

def test_assumptions():
    for arg, testfunc in assumptions.iteritems():
        result = testfunc(arg)
        if result:
            yield result

assumptions.py

from assume import have, assumed, simple_assumptions
import oe.process
import os.path

simple_assumptions(have,
    'fakeroot',
    'pseudo',
    'sed',
    'grep',
    'unzip',
    'patch',
    'diffstat',
    'cvs',
    'bzip2',
    'bc',
    'chrpath',
    'quilt',
    'git',

    'bison',
    'flex',
    'gperf',
    'gzip',
    'gperf',
    # 'gettext', - not safe atm, some recipes grab config.rpath directly from
    # the oe sysroot

    **{
        'svn': 'subversion-native',
        'makeinfo': 'texinfo-native',
        'eu-strip': 'elfutils-native',
    }
)

simple_assumptions(check=os.path.exists, **{
    '/usr/lib/libz.a': 'zlib-native',
    '/usr/lib/libcurl.a': 'curl-native',
    '/usr/lib/libreadline.a': 'readline-native',
    #    '/usr/lib/libsqlite3.a': 'sqlite3-native',
    '/usr/lib/libuuid.a': 'util-linux-native',
})

def gnu_version(name, minversion):
    try:
        veroutput = oe.process.run([name, '--version'])
    except oe.process.CmdError:
        return None

    firstline = veroutput.splitlines()[0]
    strversion = firstline.split()[-1]

    version = [int(c) for c in strversion.split('.')]
    if version >= minversion:
        return '%s-native' % name

@assumed
def m4():
    return gnu_version('m4', [1, 4, 6])

@assumed
def tar():
    return gnu_version('tar', [1, 20])