codecs.EncodedFile

[Neil Cerutti]

Perhaps I'm just bad at searching for bugs, but anyhow, I wanted
to know what you all thought about the following behavior.

A quick search of pydev archives yielded a nice wrapper to apply
to streams to perform decoding and encoding behind the scenes.
Assuming I get the correct encodings from somewhere (that's a
whole 'nother thread):

Here's the docs:

EncodedFile( file, input[, output[, errors]]) 

  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 strings 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. 

Base on that, I wrote the following code at startup:

  sys.stdout = codecs.EncodedFile(sys.stdout, 'latin-1', 'cp437')
  sys.stdin = codecs.EncodedFile(sys.stdin, 'cp437', 'latin-1')

Now my application never returns from its first call to
sys.stdin.readline.

It turns out to be troublesome for my case because the
EncodedFile object translates calls to readline into calls to
read.

I believe it ought to raise a NotImplemented exception when
readline is called. 

As it is it silently causes interactive applications to
apparently hang forever, and breaks the line-buffering
expectation of non-interactive applications.

If raising the exception is too much to ask, then at least it
should be documented better.

-- 
Neil Cerutti
The choir invites any member of the congregation who enjoys
sinning to join the choir. --Church Bulletin Blooper