Weird Python error after extending a class

vkr.mobile — Sun, 10 Jul 2022 09:46:35 GMT

I've asked this question on a Python Discord server, but the people that helped me there were not able to help me with this one. I'm hoping someone here can help me with the extended class of which Fusion Python says cannot access a member of the parent class.

The error I get is:

File "/Users/user/Library/Application Support/Autodesk/Autodesk Fusion 360/API/Scripts/NewScript1/modules/VKR/order.py", line 86, in __init__ app.log(str(self.__filesWithInfo)) AttributeError: 'PriorityFiles' object has no attribute '_PriorityFiles__filesWithInfo'

Since there are no line-numbers in the snippet, I've added a comment of #error in the line that produces the error. As far as I can see, I've correctly extended the FilesWithInfo class with the PriorityFiles class. Yet, the child-class does not seem to have access to the parent's class member self.__filesWithInfo. What am I doing wrong?

''' Module to handle checking if there are files to be processed. ''' import adsk.core, adsk.fusion, adsk.cam, traceback import os from ..VKR.options import OPTIONS app = adsk.core.Application.get() class OrderFile: ''' A file that has been found in the orders directory that needs to be prioritized ''' def __init__( self, name: str ): self.name: str = name self._mod_time: int = None self._priority_level: int = 0 def mod_time( self ) -> int: ''' Modification time ''' return self._mod_time _time.setter def mod_time( self, time: int ): self._mod_time = time def priority_level( self ) -> int: ''' The priority level of the file ''' return self._priority_level _level.setter def priority_level( self, priority: int ): self._priority_level = priority class FilesWithInfo: ''' A holder for filenames with information stored about the files ''' def __init__( self, files: list[ OrderFile ] = [] ): self.__filesWithInfo = files def add( self, file: OrderFile ): ''' Add a file with information to the storage ''' self.__filesWithInfo.append( file ) def length( self ): ''' Return the amount of stored files ''' return len( self.__filesWithInfo ) def priorities( self ) -> list[ OrderFile ] or None: ''' Return only the files that have priority or return None ''' ret = list( filter( lambda x: int( x.priority_level ) > 0, self.__filesWithInfo )) ret2 = PriorityFiles( ret ) return ret2 if ret2.length > 0 else None def oldest( self, files: list[ OrderFile ] ) -> OrderFile: ''' Return the oldest file ''' ret = None for x in files: if ret and x.mod_time < ret.mod_time: ret = x return ret class PriorityFiles( FilesWithInfo ): ''' FilesWithInfo, but then for priority files only ''' def __init__( self, files: list[ OrderFile ] = [] ): super().__init__( files ) app.log(str(self.__filesWithInfo)) #error def highest( self ) -> OrderFile: ''' Return the filename that has the highest priority ''' highest = None for f in self.__filesWithInfo: if highest: highest = f if f.priority_level > highest.priority_level else highest elif not highest: highest = f return highest class Order: ''' Find files to process in the designated directory ''' def __init__( self, path ): self.__currentDirList = os.listdir() self.__currentFileInfo = FilesWithInfo() self.__nextOrder = '' self.__done = True return def check( self ) -> OrderFile or None: ''' Check if there are orders that need to be processed ''' self.__oldDirList = self.__currentDirList self.__currentDirList = os.listdir() self.__currentFileInfo = FilesWithInfo( self._getFileInformation( self.__currentDirList )) if len( self.__currentDirList ) > 0: self.__nextOrder = self._selectOrder( self.__currentFileInfo ) return self.__nextOrder else: return None def _selectOrder( self, fileInfo: FilesWithInfo ): ''' Select an order to be processed next by applying selection priority criteria ''' prio = fileInfo.priorities if isinstance(fileInfo, FilesWithInfo ) else None nextOrder = None if isinstance( prio, PriorityFiles ): nextOrder = prio.highest elif isinstance( fileInfo, FilesWithInfo ): nextOrder = fileInfo.oldest return nextOrder def _getFileInformation( self, files: [str] ) -> FilesWithInfo: ''' Run through all the found files and return a Dictionary of OrderFiles ''' ret = [] for name in files: f_stats = os.stat( name ) newFileInfo = OrderFile( name ) OrderFile.mod_time = f_stats.st_mtime OrderFile.priority_level = self._getPriorityLevel( name ) ret.append( OrderFile ) return ret def _getPriorityLevel( self, name: str ) -> int: ''' Find if a filename has priority or not and if so, return the priority level ''' if 'priority' in name: tmp = name.split( '_' ) locationOfPriority = tmp.index( 'priority' ) + 1 return tmp[ locationOfPriority ] else: return 0

Re: Weird Python error after extending a class

Jorge_Jaramillo — Sun, 10 Jul 2022 17:26:54 GMT

Hi,

It's hard to find the error with the information you provided.

Printing the callstack with traceback module is very handy:

import traceback .... try: app.log(str(self.__filesWithInfo)) #error except: app.log(f'Traceback: {traceback.format_exc()}')

Nevertheless, if your idea with the PriorityFiles class is to find the item with the highest priority, you can replace it with a lambda's function (see next snip) which could be implemented in a FilesWithInfo's method (that way you get rid out of the class PriorityFiles) :

max(file_list, key=lambda x: x.priority_level)

Also notice that it is strange that PriorityFiles being a subclass of FilesWithInfo, you use an instance of it own subclass PriorityFiles.

Finally, this is just a Python question, and nothing to be related with Fusion 360 API behavior.

Hope this could help you.

Regards,

Jorge

Re: Weird Python error after extending a class

vkr.mobile — Mon, 11 Jul 2022 12:39:30 GMT

Apparently, properties with a double underscore are somewhat enforced as 'private' properties so that subclasses don't have easy access to them.

Thanks for the help

Re: Weird Python error after extending a class

Jorge_Jaramillo — Mon, 11 Jul 2022 12:33:27 GMT

Hi @vkr.mobile ,

I was referring to this method in FilesWithInfo:

def priorities( self ) -> list[ OrderFile ] or None: ''' Return only the files that have priority or return None ''' ret = list( filter( lambda x: int( x.priority_level ) > 0, self.__filesWithInfo )) ret2 = PriorityFiles( ret ) return ret2 if ret2.length > 0 else None

You are creating an object of a subclass (class PriorityFiles(FilesWithInfo) ) inside it's parent class (FilesWithInfo).

I'd suggest to add a highest() method (same as you have with oldest() method) inside FilesWithInfo class with the lambda expression I already send you and to remove the PriorityFiles class, which is causing the problem. At least just to try.

Regards,

Jorge

Re: Weird Python error after extending a class

vkr.mobile — Mon, 11 Jul 2022 12:40:44 GMT

Yeah, not very elegant. I'll change it. Thanks for the tip

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