gean 0.0.8

A minimal IOC container inspired by Spring

gean

A minimal IOC container inspired by Spring.

Install

python3 -m pip install gean

Requirements

gean, like Spring, relies on types and signatures to build and resolve the dependency graph.

Required language features:

• PEP 484 - Type Hints (Python 3.5+)
• PEP 526 - Syntax for Variable Annotations (Python 3.6+)

Features

Type hierarchies

A dependency of a given type X is exposed not only as X but also all of its super types, including generic interfaces.

class A: pass
class B(Generic[T]): pass
class C(A, B[int]): pass

container = Container()
container.register_class(C)

# All of these return the same instance of C
container.resolve(A)
container.resolve(B[int])
container.resolve(C)

Autowiring

class Subject:
  def work(self):
    print('working')

class Manager:
  subject: Subject  # will be autowired
  def run(self):
    self.subject.work()

container = Container()
# Order of registration does not matter
container.register_class(Manager)
container.register_class(Subject)

# This prints 'working'
container.resolve(Manager).run()

Modules

A module is a class whose name ends in Module.

A module may declaratively @include other classes or modules.

class PingService:
  def ping(self, addr): ...

class DNSService:
  def resolve(self, name): ...

@include(
  DNSService,
  PingService,
)
class NetworkModule: pass

def Application:
  dns_service: DNSService
  ping_service: PingService
  def run(self):
    ping_service.ping(dns_service.resolve('garciat.com'))

@include(
  NetworkModule,
  Application,
)
class ApplicationModule: pass

container = Container()
# No other dependencies need to be declared manually
# Because the modules do so declaratively
container.register_module(ApplicationModule)

container.resolve(Application).run()

Singletons

container = Container()
# Both dependencies are of type `str`
container.register_instance('/tmp', name='tmp_dir')
container.register_instance('/home/garciat', tmp='user_dir')

# Disambiguate with name
container.resolve(str, name='tmp_dir')

History

gean started off as a gist I created to show @alexpizarroj how my team leverages Spring in our projects.