On-demand function sharing [closed]

It's difficult to tell what is being asked here. This question is ambiguous, vague, incomplete, overly broad, or rhetorical and cannot be reasonably answered in its current form. For help clarifying this question so that it can be reopened, visit t开发者_如何转开发he help center. Closed 11 years ago.

I need to convert from strings to the code named references. The only currently known option is a script that makes a script, and I was thinking it could be inline like exec.

class finder:
  def __init__(self, parent):
    self.parent = parent
  def isin(self, what):
    return what in self.parent
  def find(self, what):
    if self.isin(what): return self.parent.__dict__[what.__name__]
    else: return __import__("pull").__dict__["downloader"](self.parent.hosts).download(what)
  def put(self, what):
    f = self.find(what)
    self.parent.__dict__[f.__name__] = f

from sock import Socket
from unpack import unpacker

...

class downloader:
  def __init__(self, hosts):
    self.hosts = hosts
  def download(name):
    for host in hosts:
      pack = unpacker()
      s = Socket(host[0], host[1])
      s.send("get " + name)
      f = pack.unpack(s)
      if f is not None: return f

---

I may be wrong, but I think what you're looking for is the ability to find the symbol for a method or attribute based on a string that is determined at runtime. If that's the case, I would pursue a different approach than a strategy based around exec or eval which have problems, like potential python injection attacks and tricky debugging...

In python everything is an object, including modules, classes and methods. How this helps you is that a module, let's call it spam may have a method, let's call it eggs you can access the eggs method by it's name like this:

spam.__dict__['eggs']

Now you may be asking "But how do I find the spam module by it's name?" This can done by importing the module by name using __import__:

spam = __import__('spam')

So, to call the eggs method with no arguments:

s = __import__('spam')
e = s.__dict__['eggs']
e()

---

Try eval

>>> a = 'hi'

>>> b = 'a'

>>> eval(b)

'hi'