PackageInstaller | DependencyWalker

Installer.py

class Node(object):
    def __init__(self, name):
        self.name = name
        self.deps = []
    def make_dep(self, node):
        if node not in self.deps:
            self.deps.append(node)
    def install(self):
        # install all depedencies & pkg
        resolved = []
        Node.resolver(self, resolved, [])
        for node in resolved:
            print "Installing..", node.name
    def remove(self):
        # remove all depedencies & pkg
        # TBD: olny remove unshared deps
        resolved = []
        Node.resolver(self, resolved, [])
        for node in resolved:
            print "Removing..", node.name
    def resolver(node, resolved, unresolved):
       unresolved.append(node)
       for dep in node.deps:
              if dep not in resolved:  # check if a dep is already resolved
                     if dep in unresolved:  # check for circular depedency
                            raise Exception('Circular depedencies detected: %s -> %s' % (node.name, dep.name))
                     Node.resolver(dep, resolved, unresolved)
       resolved.append(node)
       unresolved.remove(node)


a = Node('a')
b = Node('b')
c = Node('c')
d = Node('d')
e = Node('e')

a.make_dep(b)    # a depends on b
a.make_dep(d)    # a depends on d
b.make_dep(c)    # b depends on c
b.make_dep(e)    # b depends on e
c.make_dep(d)    # c depends on d
c.make_dep(e)    # c depends on e

b.install()
b.remove()

#OUTPUT###
Installing.. d
Installing.. e
Installing.. c
Installing.. b
Removing.. d
Removing.. e
Removing.. c
Removing.. b