io.UnsupportedOperation when calling tell()

Problem description

Performing a file_obj.tell() on a file object returned by smart_open.open results in an error in the 4.1.2 release. However, when I switch to the previous 4.1.0 release, this does not occur. A quick search seems to point to #578 which introduces use of io.TextIOWrapper. Calling tell() is not using the underlying tell() from the cloud specific writers. The original codecs implementation inherits functions like tell() from the file object that is passed in.

Steps/code to reproduce the problem

cloud_location = 's3://examplebucket/foobar'
import smart_open
with smart_open.open(cloud_location, 'w') as f:
    print(f.tell())

Above code with a valid cloud_location throws the following:

Traceback (most recent call last):
  File "<stdin>", line 2, in <module>
io.UnsupportedOperation: underlying stream is not seekable

Versions

Linux-5.4.0-1029-aws-x86_64-with-glibc2.29 Python 3.8.5 (default, Jul 28 2020, 12:59:40) [GCC 9.3.0] smart_open 4.1.2

Checklist

Before you create the issue, please make sure you have:

• Described the problem clearly
• Provided a minimal reproducible example, including any required data
• Provided the version numbers of the relevant software

[markopy]

Strange, from a quick look at TextIOWrapper it should be calling the underlaying tell(). I will add some additional tests and investigate.

[quantumfusion]

I see. Thanks for the clarification. Sounds like we need to go through and clean up our usage of tell(). Luckily it seems to only be used for a bunch of logging…