Depsolver with alternative version

debian_version_example.py

from depsolver import PackageInfo, Repository, Pool, Request, Requirement, Solver
from depsolver.debian_version import DebianVersion

P = PackageInfo.from_string
R = Requirement.from_string
V = DebianVersion.from_string

a_1_0_0 = P("A-1.0.0~1; depends (B, C)", V)
b_1_0_0 = P("B-1.0.0~1; depends (D <= 1.1.0~1)", V)
c_1_0_0 = P("C-1.0.0~1; depends (D <= 0.9.0~1)", V)
d_1_1_0 = P("D-1.1.0~1", V)
d_0_9_0 = P("D-0.9.0~1", V)

repo = Repository([a_1_0_0, b_1_0_0, c_1_0_0, d_1_1_0, d_0_9_0])
installed_repo = Repository()
pool = Pool([repo, installed_repo])

# despolver resolves each dependency 'globally', and does not install
# D-1.1.0 as pip currently does
request = Request(pool)
request.install(R("A", V))
for operation in Solver(pool, installed_repo).solve(request):
    print operation