如何在类创建时使用self.method（）？

Question

In some cases, I want to use instance method in class creation time.

I just want to use self in permissions list..This is my question

But it does not work. Is it some ways to solve the problem?

class PermissionChecker(object):
    # how to use self in class create time.
    permissions = [self.is_superuser(), self.is_god()]

    def is_superuser(self):
        # use self.property just like self.name...
        return True

    def is_god(self):
        return True

class Child(PermissionChecker):
    permissions = PermissionChecker.permissions + [self.is_coder(),]

    def is_coder(self):
        return True

Answer 1

It looks like you are confusing the term attribute with property ; you cannot use self in the class definition itself, it is only available to a method.

I think you are looking for the property descriptor :

class PermissionChecker(object):
    @property
    def permissions(self):
        return [self.is_superuser(), self.is_god()]

    def is_superuser(self):
        # use self.property just like self.name...
        return True

    def is_god(self):
        return True

By using property (above used as a @ decorator) you turn a method into an attribute:

>>> pcheck = PermissionChecker()
>>> pcheck.permissions
[True, True]

The permissions method is called every time the .permissions attribute is accessed on an instance.

Alternatively, set the list in the __init__ initializer:

class PermissionChecker(object):
    def __init__(self):
        self.permissions = [self.is_superuser(), self.is_god()]

    def is_superuser(self):
        # use self.property just like self.name...
        return True

    def is_god(self):
        return True

Answer 2

It looks like you are trying to provide a property. This can be done like so:

class PermissionChecker(object):
    def _get_permissions(self):
        return [self.is_superuser(), self.is_god()]

    permissions = property(_get_permissions)

    def is_superuser(self):
        # use self.property just like self.name...
        return True

    def is_god(self):
        return True