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Dive Into Python-Chapter 5. Objects and Object-Orientation

Tham khảo tài liệu 'dive into python-chapter 5. objects and object-orientation', công nghệ thông tin, kỹ thuật lập trình phục vụ nhu cầu học tập, nghiên cứu và làm việc hiệu quả | Chapter 5. Objects and Object-Orientation This chapter and pretty much every chapter after this deals with object-oriented Python programming. 5.1. Diving In Here is a complete working Python program. Read the doc strings of the module the classes and the functions to get an overview of what this program does and how it works. As usual don t worry about the stuff you don t understand that s what the rest of the chapter is for. Example 5.1. fileinfo .py If you have not already done so you can download this and other examples used in this book. Framework for getting filetype-specific metadata. Instantiate appropriate class with filename. Returned object acts like a dictionary with key-value pairs for each piece of metadata. import fileinfo info fileinfo.MP3FileInfo music ap mahadeva.mp3 print n .join s s k v for k v in info.items Or use listDirectory function to get info on all files in a directory. for info in fileinfo.listDirectory music ap .mp3 Framework can be extended by adding classes for particular file types e.g. HTMLFileInfo MPGFileInfo DOCFileInfo. Each class is completely responsible for parsing its files appropriately see MP3FileInfo for example. import os import sys from UserDict import UserDict def stripnulls data strip whitespace and nulls return data.replace 00 .strip class FileInfo UserDict store file metadata def __init self filename None UserDict.init__ self self name filename class MP3FileInfo FileInfo store ID3v1.0 MP3 tags tagDataMap title 3 33 stripnulls artist 33 63 stripnulls album 63 93 stripnulls year 93 97 stripnulls comment 97 126 stripnulls genre 127 128 ord def __parse self filename parse ID3v1.0 tags from MP3 file self.clear try fsock open filename rb 0 try fsock.seek -128 2 tagdata fsock.read 128 finally fsock.close if tagdata 3 TAG for tag start end parseFunc in self.tagDataMap.items self tag parseFunc tagdata start end except lOError pass def __setitem self key item if key name and item self.__parse item .