Asp Forum - Pylint Argument number differs from overridden method

Wanderer

3/3/2010 5:40:00 PM

Pylint W0221 gives the warning
Argument number differs from overridden method.

Why is this a problem? I'm overriding the method to add additional
functionality.

This
def GetRays(self, angle, pt, lmbda = 0.6):
"""
"""

angle, x, y, Rays, Power = self.ARefract(angle, pt[0], pt[1],
lmbda)
pt1 = (x, y)

return Rays, Power, angle, pt1

def ARefract(self, angle, x, y, lmbda = 0.6):
"""
"""

Nt = self.Mat.NtGet(lmbda)
self.NtSet(Nt)
angle, x, y, Rays, Power = self.Refract(angle, x, y)

return angle, x, y, Rays, Power

Over rides this

def GetRays(self, angle, pt):
"""
"""

angle, x, y, Rays, Power = self.Refract(angle, pt[0], pt[1])
pt1 = (x, y)

return Rays, Power, angle, pt1

Thanks

5 Answers

Robert Kern

3/3/2010 7:34:00 PM

On 2010-03-03 11:39 AM, Wanderer wrote:
> Pylint W0221 gives the warning
> Argument number differs from overridden method.
>
> Why is this a problem? I'm overriding the method to add additional
> functionality.

There are exceptions to every guideline. Doing this could easily be a mistake,
so it's one of the many things that Pylint checks for. Silence the warning if
you like.

--
Robert Kern

"I have come to believe that the whole world is an enigma, a harmless enigma
that is made terrible by our own mad attempt to interpret it as though it had
an underlying truth."
-- Umberto Eco

Wanderer

3/3/2010 9:15:00 PM

On Mar 3, 2:33 pm, Robert Kern <robert.k...@gmail.com> wrote:
> On 2010-03-03 11:39 AM, Wanderer wrote:
>
> > Pylint W0221 gives the warning
> > Argument number differs from overridden method.
>
> > Why is this a problem? I'm overriding the method to add additional
> > functionality.
>
> There are exceptions to every guideline. Doing this could easily be a mistake,
> so it's one of the many things that Pylint checks for. Silence the warning if
> you like.
>
> --
> Robert Kern
>
> "I have come to believe that the whole world is an enigma, a harmless enigma
> that is made terrible by our own mad attempt to interpret it as though it had
> an underlying truth."
> -- Umberto Eco

Thanks I was just wondering if I was overlooking something about
inheritance.

Terry Reedy

3/3/2010 9:17:00 PM

On 3/3/2010 12:39 PM, Wanderer wrote:
> Pylint W0221 gives the warning
> Argument number differs from overridden method.
>
> Why is this a problem?

It *could* indicate a mistake. Lint programs, by definition, are
nitpicky, and flag things that are possible problems even though
syntactically correct.

I'm overriding the method to add additional
> functionality.
>
> This
> def GetRays(self, angle, pt, lmbda = 0.6):
> """
> """
>
> angle, x, y, Rays, Power = self.ARefract(angle, pt[0], pt[1],
> lmbda)
> pt1 = (x, y)
>
> return Rays, Power, angle, pt1
>
>
> def ARefract(self, angle, x, y, lmbda = 0.6):
> """
> """
>
> Nt = self.Mat.NtGet(lmbda)
> self.NtSet(Nt)
> angle, x, y, Rays, Power = self.Refract(angle, x, y)
>
> return angle, x, y, Rays, Power
>
>
>
> Over rides this
>
> def GetRays(self, angle, pt):
> """
> """
>
> angle, x, y, Rays, Power = self.Refract(angle, pt[0], pt[1])
> pt1 = (x, y)
>
> return Rays, Power, angle, pt1
>
>
> Thanks

Jean-Michel Pichavant

3/4/2010 10:45:00 AM

Wanderer wrote:
> On Mar 3, 2:33 pm, Robert Kern <robert.k...@gmail.com> wrote:
>
>> On 2010-03-03 11:39 AM, Wanderer wrote:
>>
>>
>>> Pylint W0221 gives the warning
>>> Argument number differs from overridden method.
>>>
>>> Why is this a problem? I'm overriding the method to add additional
>>> functionality.
>>>
>> There are exceptions to every guideline. Doing this could easily be a mistake,
>> so it's one of the many things that Pylint checks for. Silence the warning if
>> you like.
>>
>> --
>> Robert Kern
>>
>> "I have come to believe that the whole world is an enigma, a harmless enigma
>> that is made terrible by our own mad attempt to interpret it as though it had
>> an underlying truth."
>> -- Umberto Eco
>>
>
> Thanks I was just wondering if I was overlooking something about
> inheritance.
>
This is only my opinion but you get this warning because of 2 disctinct
issues:
1/ you just made a basic mistake in your signature and need to correct it
2/ you did not make any mistake in the signature, but this warning may
reveal a (small) flaw in your class design.

I don't know the exact context for your code, but it's better to have a
consistant interface over your methods and mask the implementation
details from the user.
In your case, the getRays method may always ask for the lambda
parameters and just ignore it for one of its implementation.

And don't write empty doctrings to trick pylint. Either write them, or
remove this rule, you are loosing all the tool benefits.

JM

Wanderer

3/4/2010 8:49:00 PM

On Mar 4, 5:45 am, Jean-Michel Pichavant <jeanmic...@sequans.com>
wrote:
> Wanderer wrote:
> > On Mar 3, 2:33 pm, Robert Kern <robert.k...@gmail.com> wrote:
>
> >> On 2010-03-03 11:39 AM, Wanderer wrote:
>
> >>> Pylint W0221 gives the warning
> >>> Argument number differs from overridden method.
>
> >>> Why is this a problem? I'm overriding the method to add additional
> >>> functionality.
>
> >> There are exceptions to every guideline. Doing this could easily be a mistake,
> >> so it's one of the many things that Pylint checks for. Silence the warning if
> >> you like.
>
> >> --
> >> Robert Kern
>
> >> "I have come to believe that the whole world is an enigma, a harmless enigma
> >> that is made terrible by our own mad attempt to interpret it as though it had
> >> an underlying truth."
> >> -- Umberto Eco
>
> > Thanks I was just wondering if I was overlooking something about
> > inheritance.
>
> This is only my opinion but you get this warning because of 2 disctinct
> issues:
> 1/ you just made a basic mistake in your signature and need to correct it
> 2/ you did not make any mistake in the signature, but this warning may
> reveal a (small) flaw in your class design.
>
> I don't know the exact context for your code, but it's better to have a
> consistant interface over your methods and mask the implementation
> details from the user.
> In your case, the getRays method may always ask for the lambda
> parameters and just ignore it for one of its implementation.
>
> And don't write empty doctrings to trick pylint. Either write them, or
> remove this rule, you are loosing all the tool benefits.
>
> JM

Okay different example. I'm not really using inheritance here but its
the same idea.
The wx.SpinCtrl is annoyingly integer. I want decimal values. so I
created dSpinCtrl.
It adds the argument places. It's a drop in replacement for SpinCtrl.
(okay its not, because I didn't create all the members). If you
replace SpinCtrl with dSpinCtrl the program should work the same
because the new argument places has a default value. I don't see a
problem with more arguments. Less arguments would be a problem.
Expanding functionality from a base class is what I thought
inheritance is about.

class dSpinCtrl():
"""Adds decimal values to SpinCtrl. Almost a drop in replacement
for SpinCtrl.
Adds 'places' variable for number of places after decimal point
"""

def __init__ (self,
parent,
iD = ID_SPIN,
value = wx.EmptyString,
pos = wx.DefaultPosition,
size = wx.DefaultSize,
style = wx.SP_ARROW_KEYS,
dmin = -100.0,
dmax = 100.0,
dinitial = 0.0,
places = 0):

comp.lang.python

Pylint Argument number differs from overridden method

Wanderer

Robert Kern

Wanderer

Terry Reedy

Jean-Michel Pichavant

Wanderer

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