arcpy, CalculateField: 'geoprocessing sys.stdout object' object has no attribute 'flush'

Question

Working with 10.2.2, 64bit geoprocessing arcpy installation. Getting this error from arcpy.CalculateField_management() command.

From Spyder IDE in an ipython console, I get the error:

[IPKernelApp] ERROR | Exception in message handler:
Traceback (most recent call last):
  File "C:\Users\Nick\appdata\local\enthought\canopy\user\lib\site-packages\IPython\kernel\zmq\ipkernel.py", line 245, in dispatch_shell
    handler(stream, idents, msg)
  File "C:\Users\Nick\appdata\local\enthought\canopy\user\lib\site-packages\IPython\kernel\zmq\ipkernel.py", line 400, in execute_request
    reply_content.update(shell._showtraceback(etype, evalue, tb_list))
  File "C:\Users\Nick\appdata\local\enthought\canopy\user\lib\site-packages\IPython\kernel\zmq\zmqshell.py", line 501, in _showtraceback
    sys.stdout.flush()
AttributeError: 'geoprocessing sys.stdout object' object has no attribute 'flush'

It doesn't seem to have anything to do with the specifics of the command, and I can execute most other arcpy commands without problem.

Suggestions?

Here's the code I was running to get up to this (although I've tried this with different targets and different expressions -- it just seems to be the command, not the specifics):

ap.CalculateField_management(in_table = thiessens, field = 'primarySiteID', 
                             expression = "!SITEID!",
                             expression_type = 'PYTHON')

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At this point I'm pretty sure it's an incompatibility with iPython that only appears in the context of some of the field-editing commands (since I use iPython all the time and usually without issue...)

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Pretty sure it's iPython -- have the same issue with a different ipython install on a different computer, so I don't think it's Spyder or that specific installation.

Answer 1

Part of the problem is the way the CalculateField_management tool is coded. It almost certainly uses the Python command sys.stdout.flush(), which is misinterpreted by ArcGIS as a geoprocessing object.

I ran into this problem with code that I wrote with sys.stdout.flush(). The simple solution was to remove sys.stdout.flush() to avoid the conflicts, which is a patch ESRI could implement.

I don't know what in ArcGIS is causing it to be interpreted as a geoprocessing object. This seems to depend on how you run the code. I do not get an error when I run the code in a normal console in Spyder on a separate install of Python (Anaconda), but I do get the error when I run the code from an ArcGIS toolbox on the default Python installation.

FYI: sys is the system module in Python. sys.stdout.flush() tells Python to write any print statements immediately (printing is slow, so by default Python may wait to print). See more here: https://stackoverflow.com/questions/10019456/usage-of-sys-stdout-flush-method