This module defines base classes for standard Python codecs (encoders and decoders) and provides access to the internal Python codec registry which manages the codec lookup process.
It defines the following functions:
(encoder, decoder, stream_reader, stream_writer)taking the following arguments:
encoder and decoder: These must be functions or methods which have the same interface as the .encode/.decode methods of Codec instances (see Codec Interface). The functions/methods are expected to work in a stateless mode.
stream_reader and stream_writer: These have to be factory functions providing the following interface:
The factory functions must return objects providing the interfaces defined by the base classes StreamWriter and StreamReader, respectively. Stream codecs can maintain state.
Possible values for errors are
'strict' (raise an exception
in case of an encoding error),
'replace' (replace malformed
data with a suitable replacement marker, such as "?") and
'ignore' (ignore malformed data and continue without further
In case a search function cannot find a given encoding, it should
Encodings are first looked up in the registry's cache. If not found, the list of registered search functions is scanned. If no codecs tuple is found, a LookupError is raised. Otherwise, the codecs tuple is stored in the cache and returned to the caller.
To simplify working with encoded files or stream, the module also defines these utility functions:
Note: The wrapped version will only accept the object format defined by the codecs, i.e. Unicode objects for most builtin codecs. Output is also codec dependent and will usually by Unicode as well.
encoding specifies the encoding which is to be used for the the file.
errors may be given to define the error handling. It defaults to 'strict' which causes a ValueError to be raised in case an encoding error occurs.
buffering has the same meaning as for the built-in open() function. It defaults to line buffered.
Return a wrapped version of file which provides transparent encoding translation.
Strings written to the wrapped file are interpreted according to the given input encoding and then written to the original file as string using the output encoding. The intermediate encoding will usually be Unicode but depends on the specified codecs.
If output is not given, it defaults to input.
errors may be given to define the error handling. It defaults to 'strict' which causes ValueError to be raised in case an encoding error occurs.
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The module also provides the following constants which are useful for reading and writing to platform dependent files: