PyEcore Documentation

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PyEcore is a Model Driven Engineering (MDE) framework written for Python. It is an implementation of EMF/Ecore for Python, and tries to give an API compatible with the original EMF Java implementation.

PyEcore allows you to create, load, modify, save and interact with models and metamodels, to provide a framework to build MDE-based tools and other applications based on a structured data model. It supports:

  • Data inheritance
  • Two-way relationship management (opposite references)
  • XMI serialization and deserialization
  • JSON serialization and deserialization
  • Notification system
  • Reflexive API

This example shows creation of simple “dynamic” metamodel (in contrast to a static metamodel, as shown in “User Documentation”):

>>> from pyecore.ecore import EClass, EAttribute, EString, EObject
>>> Graph = EClass('Graph')  # We create a 'Graph' concept
>>> Node = EClass('Node')  # We create a 'Node' concept
>>>
>>> # We add a "name" attribute to the Graph concept
>>> Graph.eStructuralFeatures.append(EAttribute('name', EString,
                                                default_value='new_name'))
>>> # And one on the 'Node' concept
>>> Node.eStructuralFeatures.append(EAttribute('name', EString))
>>>
>>> # We now introduce a containment relation between Graph and Node
>>> contains_nodes = EReference('nodes', Node, upper=-1, containment=True)
>>> Graph.eStructuralFeatures.append(contains_nodes)
>>> # We add an opposite relation between Graph and Node
>>> Node.eStructuralFeatures.append(EReference('owned_by', Graph, eOpposite=contains_nodes))

With this code, we have defined two concepts: Graph and Node. Both have a name, and there exists a containment relationship between them. This relation is bi-directionnal, which means that each time a Node object is added to the nodes relationship of a Graph, the owned_by relation of the Node is also updated also. The reverse is also true, if a Graph were added to Node.owned_by.

Let’s create some instances of our freshly created metamodel:

>>> # We create a Graph
>>> g1 = Graph(name='Graph 1')
>>> g1
<pyecore.ecore.Graph at 0x7f0055554dd8>
>>>
>>> # And two node instances
>>> n1 = Node(name='Node 1')
>>> n2 = Node(name='Node 2')
>>> n1, n2
(<pyecore.ecore.Node at 0x7f0055550588>,
 <pyecore.ecore.Node at 0x7f00555502b0>)
>>>
>>> # We add them to the Graph
>>> g1.nodes.extend([n1, n2])
>>> g1.nodes
EOrderedSet([<pyecore.ecore.Node object at 0x7f0055550588>,
             <pyecore.ecore.Node object at 0x7f00555502b0>])
>>>
>>> # bi-directional references are updated
>>> n1.owned_by
<pyecore.ecore.Graph at 0x7f0055554dd8>

This example gives a quick overview of some of the features you get when using PyEcore.

Indices and tables