如何在Python中模拟赋值运算符重载? [英] How to Emulate Assignment Operator Overloading in Python?

问题描述

如何在Python中模拟赋值运算符重载?例如...

How can you emulate assignment operator overloading in Python? For example...

class Example(object):

    name = String()
    age = Integer()

    def __init__(self,myname,myage):
        self.name.value = myname
        self.age.value = myage

除了执行self.name.value = name之外，还可以如何模拟赋值运算符的重载，以便在执行self.name = myname时将myname分配给self.name.value?

Rather than doing self.name.value = name, how can you emulate overloading of the assignment operator so that myname is assigned to self.name.value when you do self.name = myname?

推荐答案

我最终创建了一个名为ModelMeta的模型元类，用于注册类型化属性.

I ended up creating a Model metaclass called ModelMeta that registers the typed attributes.

请参见 http://github.com/espeed/bulbs/blob /master/bulbs/model.py

在这种情况下，键入的属性是图形数据库属性"，它们都是Property类的所有子类.

In this case, the typed attributes are graph-database "properties", which are all subclasses of the Property class.

请参见 https://github.com/espeed/bulbs/blob /master/bulbs/property.py

这是示例模型声明:

# people.py

from bulbs.model import Node, Relationship
from bulbs.property import String, Integer, DateTime
from bulbs.utils import current_datetime

class Person(Node):

    element_type = "person"

    name = String(nullable=False)
    age = Integer()


class Knows(Relationship):

    label = "knows"

    created = DateTime(default=current_datetime, nullable=False)

示例用法:

>>> from people import Person
>>> from bulbs.neo4jserver import Graph
>>> g = Graph()

# Add a "people" proxy to the Graph object for the Person model:
>>> g.add_proxy("people", Person)

# Use it to create a Person node, which also saves it in the database:
>>> james = g.people.create(name="James")
>>> james.eid
3
>>> james.name
'James'

# Get the node (again) from the database by its element ID:
>>> james = g.people.get(james.eid)

# Update the node and save it in the database:
>>> james.age = 34
>>> james.save()

# Lookup people using the Person model's primary index:
>>> nodes = g.people.index.lookup(name="James")

看到...

• 灯泡模型API: http://bulbflow.com/docs/api/bulbs/model /
• 灯泡模型快速入门: http://bulbflow.com/quickstart/#models

• Bulbs Model API: http://bulbflow.com/docs/api/bulbs/model/
• Bulbs Model Quickstart: http://bulbflow.com/quickstart/#models

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