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Date: Wed, 25 May 2011 17:32:58 -0700
From: Ethan Furman <ethan@stoneleaf.us>
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To: python-list@python.org
Subject: Re: Python 3.2 bug? Reading the last line of a file
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MRAB wrote:
> On 26/05/2011 00:25, tkpmep@hotmail.com wrote:
>> Thanks for the guidance - it was indeed an issue with reading in
>> binary vs. text., and I do now succeed in reading the last line,
>> except that I now seem unable to split it, as I demonstrate below.
>> Here's what I get when I read the last line in text mode using 2.7.1
>> and in binary mode using 3.2 respectively under IDLE:
>>
>> 2.7.1
>> Name    31/12/2009    0    0    0
>>
>> 3.2
>> b'Name\t31/12/2009\t0\t0\t0\r\n'
>>
>> if, under 2.7.1 I read the file in text mode and write
>>>>> x = lastLine(fn)
>> I can then cleanly split the line to get its contents
>>>>> x.split('\t')
>> ['Name', '31/12/2009', '0', '0', '0\n']
>>
>> but under 3.2, with its binary read, I get
>>>>> x.split('\t')
>> Traceback (most recent call last):
>>    File "<pyshell#26>", line 1, in<module>
>>      x.split('\t')
>> TypeError: Type str doesn't support the buffer API
>>
>> If I remove the '\t', the split now works and I get a list of bytes
>> literals
>>>>> x.split()
>> [b'Name', b'31/12/2009', b'0', b'0', b'0']
>>
>> Looking through the docs did not clarify my understanding of the
>> issue. Why can I not split on '\t' when reading in binary mode?
>>
> x.split('\t') tries to split on '\t', a string (str), but x is a
> bytestring (bytes).
> 
> Do x.split(b'\t') instead.

<nitpick>
Instances of the bytes class are more appropriately called 'bytes 
objects' rather than 'bytestrings' as they are really lists of integers. 
  Accessing a single element of a bytes object does not return a bytes 
object, but rather the integer at that location; i.e.

--> b'xyz'[1]
121

Contrast that with the str type where

--> 'xyz'[1]
'y'
</nitpick>

~Ethan~