dummytools.py: F821 Undefined name "parent"

[buhtz]

While reviewing my own PR #1448 with linters (ruff & pycodestyle) I found a possible bug. Further investigation needed.

backintime/common/dummytools.py

Line 51 in 8fbec2d

self.setattrKwargs('password', self.config.password(parent, self.profile_id), store = False, **kwargs)

Ruff says common/dummytools.py:51:61: F821 Undefined name "parent".

• When was it introduced (commit history)?
• What happens there?
• Why isn't there a known issue about that problem?
• Do we need that code if it is never reached?

[buhtz]

backintime/common/dummytools.py

Line 51 in 8fbec2d

self.setattrKwargs('password', self.config.password(parent, self.profile_id), store = False, **kwargs)

I assume that mount.MountControl.parent is meant instead of parent.

The class Dummy isn't used anywhere. It seems just to be an example about how to derive from mount.MountControl. My first suggestion would be to move this into the (user or development) documentation somewhere.

[Germar]

Have a look in sshtools.py:

backintime/common/sshtools.py

Lines 78 to 80 in 8fbec2d

	parent (QWidget): parent widget for QDialogs or ``None`` if there
	is no parent (handled by
	inherited :py:class:`mount.MountControl`)

Dummy is a template for future classes.

[buhtz]

Dear Germar,
thanks for the quick reply.

Have a look in sshtools.py:

Not sure if I interpret that correct. So you mean I'm right with my assumption that parent should be replaced with self.parent?

Dummy is a template for future classes.

I don't get that point. That code is never used.
If it is a "template" in the meaning that other developers should use that code as a start to create there own mount.MountControl based classes then I would say this should go into documentation (e.g. docstrings) and not into productive code.

[Germar]

Not sure if I interpret that correct. So you mean I'm right with my assumption that parent should be replaced with self.parent?

No, parent is a QWidget or None set in class Mount in mount.py

If it is a "template" in the meaning that other developers should use that code as a start to create there own mount.MountControl based classes then I would say this should go into documentation (e.g. docstrings) and not into productive code.

I don't care. I think it's easier to just copy dummy.py when someone starts a new mount.MountControl based classes. But you can move it into dev-doc if you like.

[buhtz]

Not sure if I interpret that correct. So you mean I'm right with my assumption that parent should be replaced with self.parent?

No, parent is a QWidget or None set in class Mount in mount.py

Sorry, I'm confused and don't get it.
Then how to solve the problem "Undefined name 'parent'"?

[Germar]

parent is defined in mount.MountControl. Dummy inherit from Mount.MountControl, so it contains all args and functions, that mount.MountControl defined.

To solve the undefined name problem you need to tell the tool to resolve the inheritance of the class

[buhtz]

I assume there is a misunderstanding. But maybe I can't see the forest for the trees. 😅

To solve the undefined name problem you need to tell the tool to resolve the inheritance of the class

The tool is able to resolve inheritance.

My point (and the problem of Python and the linter) is that the name/object parent is unknown in Dummy.__init__(). It is not a variable in the methods names space. It is not an argument.

I do understand that conceptually it is inherited from class Mount which can be seen here:

backintime/common/mount.py

Line 66 in 8fbec2d

self.parent = parent

Because of that that line

backintime/common/dummytools.py

Line 51 in 8fbec2d

self.setattrKwargs('password', self.config.password(parent, self.profile_id), store = False, **kwargs)

IMHO should be modified into

self.setattrKwargs('password', self.config.password(self.parent, self.profile_id), store = False, **kwargs) 
                                                    ^^^^^

Am I wrong here somehow? I don't want to break anything.

[aryoda]

IMHO should be modified into

self.setattrKwargs('password', self.config.password(self.parent, self.profile_id), store = False, **kwargs) 
                                                    ^^^^^

Am I wrong here somehow? I don't want to break anything.

@buhtz If think self is required here to access the attribute of the (parent) object.
Without self it would refer to local or global variable (which do not exist).

Since I wasn't sure myself I have used this example code to check this:

class Person:
  def __init__(self, fname, lname):
    self.firstname = fname
    self.lastname = lname
    self.parent = "a variable in the parent class"

  def printname(self):
    print(self.firstname, self.lastname)


class Student(Person):
  def __init__(self, fname, lname, year):
    super().__init__(fname, lname)
    self.graduationyear = year

    print(f"parent (self): {self.parent}")  # works
    # print(f"parent: {parent}")            # NameError: name 'parent' is not defined. Did you mean: 'print'?

  def welcome(self):
    print("Welcome", self.firstname, self.lastname, "to the class of", self.graduationyear)



x = Student("Mike", "Olsen", 2019)
x.welcome()

[aryoda]

@buhtz You have copied the template code of class Dummy from dummypytools.py into a doc string in mount.py via the commit 1003d36 but the code for class Dummy is still contained in dummytools.py (even though you wrote "move" in your commit message):

backintime/common/dummytools.py

Line 21 in 71c9657

class Dummy(mount.MountControl):

Was this intentional?

BTW: If "parent is a QWidget" in some cases (which I have not checked) we should refactor this with our GUI redesign since the backend logic (in common) should never see any GUI object from (e.g. use the observer pattern instead to ask a listener)

[buhtz]

@buhtz You have copied the template code of class Dummy from dummypytools.py into a doc string in mount.py via the commit 1003d36 but the code for class Dummy is still contained in dummytools.py (even though you wrote "move" in your commit message):

Autsch. I'll fix that mistake.
Reopen because common/dummytools.py still exists but should be deleted.