TensorFlow decorator to share variables between calls. Works for both functions and methods.

share_variables_decorator.py

import functools

import tensorflow as tf


class share_variables(object):

  def __init__(self, callable_):
    self._callable = callable_
    self._wrappers = {}
    self._wrapper = None

  def __call__(self, *args, **kwargs):
    return self._function_wrapper(*args, **kwargs)

  def __get__(self, instance, owner):
    decorator = self._method_wrapper
    decorator = functools.partial(decorator, instance)
    decorator = functools.wraps(self._callable)(decorator)
    return decorator

  def _method_wrapper(self, instance, *args, **kwargs):
    if instance not in self._wrappers:
      name = self._create_name(
          type(instance).__module__,
          type(instance).__name__,
          instance.name if hasattr(instance, 'name') else id(instance),
          self._callable.__name__)
      self._wrappers[instance] = tf.make_template(
          name, self._callable, create_scope_now_=True)
    return self._wrappers[instance](instance, *args, **kwargs)

  def _function_wrapper(self, *args, **kwargs):
    if not self._wrapper:
      name = self._create_name(
          self._callable.__module__,
          self._callable.__name__)
      self._wrapper = tf.make_template(
          name, self._callable, create_scope_now_=True)
    return self._wrapper(*args, **kwargs)

  def _create_name(self, *words):
    words = [str(word) for word in words]
    words = [word.replace('_', '') for word in words]
    return '_'.join(words)

share_variables_decorator_example.py

class Model(object):

  def __init__(self, name):
    self.name = name

  @share_variables
  def method(self, data):
    return tf.layers.dense(data, 100)


@share_variables
def function(data):
  return tf.layers.dense(data, 50)


data = tf.placeholder(tf.float32, [None, 50])
function(data)
function(data)
foo = Model('foo')
foo.method(data)
foo.method(data)
bar = Model('bar')
bar.method(data)

for var in tf.trainable_variables():
  print(var.name)

# Output:
# main_function/dense/kernel:0
# main_function/dense/bias:0
# main_Model_foo_method/dense/kernel:0
# main_Model_foo_method/dense/bias:0
# main_Model_bar_method/dense/kernel:0
# main_Model_bar_method/dense/bias:0

@albertz Yes, I use the object ID for the variable scope, so that different instances of the same class have their own variables. You could make it a convention that model classes must implement a model.name attribute and use that for the scope name. Or you only save/load the variables inside a scope using export_scoped_meta_graph() and import_scoped_meta_graph().

I've updated the code to include a fix and to use the self.name attribute of model classes if available, and fall back to id(self) otherwise.