Python AttributeError：“ PostSaveCommand”对象没有属性“ _server”

Question

I'm building a python plugin, the code to do this is shown below:

class BaseCommand(sublime_plugin.TextCommand):
    @property
    def server(self):
        if self._server == None:
            self._server = "My Server"
    return self._server

class PostSaveCommand(BaseCommand):
    def run(self, edit):
        super().server.new_post("Title", "", "Text")

I alway getting the following error when I try to build the code:

>>> view.run_command('post_save')
Traceback (most recent call last):
  File "/Applications/Sublime Text.app/Contents/MacOS/sublime_plugin.py", line 1088, in run_
    return self.run(edit)
  File "/Users/joywek/Library/Application Support/Sublime Text 3/Packages/BlogPress/BlogPress.py", line 53, in run
    super().server.new_post("Title", "", "Text")
  File "/Users/joywek/Library/Application Support/Sublime Text 3/Packages/BlogPress/BlogPress.py", line 42, in server
    if self._server == None:
AttributeError: 'PostSaveCommand' object has no attribute '_server'

Answer 1

We haven't defined what the attributes of sublime_plugin.TextCommand are, but assuming that _server is an attribute that you want to define as part of the BaseCommand class, you need to instantiate that attribute in an __init__ method under the BaseCommand class.

For example:

class BaseCommand(sublime_plugin.TextCommand):
    def __init__(self):
        super().__init__()
        self._server = None

    @property
    def server(self):
        if self._server == None:
            self._server = "My Server"
    return self._server

class PostSaveCommand(BaseCommand):
    def run(self, edit):
    super().server.new_post("Title", "", "Text")

With that being said, you could get rid of the server() method you've defined and simply instantiate _server to be "My Server" as you desire, such as in the example below.

class BaseCommand(sublime_plugin.TextCommand):
    def __init__(self):
        super().__init__()
        self._server = "My Server"

class PostSaveCommand(BaseCommand):
    def __init__(self):
        super().__init__()

    def run(self, edit):
        self._server.new_post("Title", "", "Text")

Answer 2

The problem is that BaseCommand does not have _server attribute set, when its server property is accessed. You are trying to check whether its None :

    if self._server == None:
        self._server = "My Server"

However, _server attribute does not exist and this check raises the AttributeError . You could instead check:

    if not hasattr(self, '_server') or self._server == None:
        self._server = 'My Server'

Which would cover both cases: when attribute does not exist and when the value of _server is equal to None .