Python: Import on Demand

import_on_demand.py

def render(engine_id, template, **kwargs):
  engines = {
    "jinja2": "jinja2",
    "mako": "make.template",
    }
    try:
      module = engines[engine_id]
      engine = __import__(
        module, globals(), locals(), ['Template'], -1)
    except (KeyError, ImportError) as err:
      print "Template engine not found!"
      return ''
    return engine.Template(template).render(**kwargs)

print render("jinja2", "Hi {{f}}", f="John")
print render("mako", "Hi ${f} ${l}", f="John", l="Doe")