[Tutor] The __setattr__ method

Justin Ko theresident@rocketmail.com
Tue, 28 Aug 2001 02:03:29 +0800

	Hey everyone. I am working on a module to provide access to an mp3 file's 
ID3 tags. A class seemed to be the best way to represent the information 
represented in an ID3 tag's fields. However, i would like to be able to 
tell when the information in the tag is changed so that the information can 
be written back into the ID3 tag. This is my dilemma.

	The __init__ method reads the information from the file.

   def __init__(self, filename = ""):
     "Initialize things to default values or read them from a file"
     if filename != "":
         file = open(filename, "r")
         file.seek(-128, 2)
         if file.read(3) == "TAG":
           self.filename = filename
           self.title = file.read(30)
           self.artist = file.read(30)
           self.album = file.read(30)
           self.year = file.read(4)
           self.comment = file.read(30)
           self.genre = self.genres[ord(file.read(1))]
           self.modified = 0

	The __setattr__ method tells me when something is changed

   def __setattr__(self, name, value):
     "Set class attributes"
     self.__dict__[name] = value
     self.__dict__['modified'] = 1

	However,  the statements in the __init__ method cause __setattr__ to be 
	So this is my question. How do I set a classes attributes without calling 
__setattr__ ? I guess it would be possible to replace all the self.variable 
= file.read( ) statements with something like self.__dict__[variable] = 
file.read( ), but that seems rather inelegant and ugly. I hope there is a 
better solution to this problem.

	- Justin Ko

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