File execution fails with AttributeError: _Feature instance has no attribute '__len__'

[AxelMKlein]

Description of your problem

1. Using from __future__ import print_function and
2. importing pdb and setting pdb.set_trace()
   lets the file-execution terminate with the error statement:
   AttributeError: _Feature instance has no attribute '__len__' .

What steps will reproduce the problem?

1. Run the following file with F5:

# -*- coding: utf-8 -*-
"""
Created on Fri Jul 28 14:47:12 2017
@author: Speedy Gonzalez
"""
from __future__ import print_function
import pdb
class speedy(object):
    def hello_world(self):
        pdb.set_trace()
        print('Hello world!')
        return
speedyo = speedy()

2. In the IPython-console type: speedyo.hello_world()

What is the expected output? What do you see instead?
Expected:

1. file starts with the debugger and the ipdb command line: ipdb>
2. After typing 'c' the words 'Hello world!' are printed in the IPython-console.

Instead the following output appears:

In [2]: speedyo.hello_world()
Traceback (most recent call last):
  File "<ipython-input-2-c923dc13a4b5>", line 1, in <module>
    speedyo.hello_world()
  File "C:/Users/Public/SVN_Workspace/ltc_2947_8_9/lab/python/axels.py", line 16, in hello_world
    print('Hello world!')
  File "C:/Users/Public/SVN_Workspace/ltc_2947_8_9/lab/python/axels.py", line 16, in hello_world
    print('Hello world!')
  File "c:\python27_64\lib\bdb.py", line 49, in trace_dispatch
    return self.dispatch_line(frame)
  File "c:\python27_64\lib\bdb.py", line 67, in dispatch_line
    self.user_line(frame)
  File "c:\python27_64\lib\pdb.py", line 158, in user_line
    self.interaction(frame, None)
  File "c:\python27_64\lib\site-packages\spyder\utils\site\sitecustomize.py", line 414, in interaction
    self.notify_spyder(frame)
  File "c:\python27_64\lib\site-packages\spyder\utils\site\sitecustomize.py", line 352, in notify_spyder
    ipython_shell.kernel.publish_pdb_state()
  File "c:\python27_64\lib\site-packages\spyder\utils\ipython\spyder_kernel.py", line 219, in publish_pdb_state
    var_properties = self.get_var_properties(),
  File "c:\python27_64\lib\site-packages\spyder\utils\ipython\spyder_kernel.py", line 132, in get_var_properties
    'len': self._get_len(value),
  File "c:\python27_64\lib\site-packages\spyder\utils\ipython\spyder_kernel.py", line 322, in _get_len
    return len(var)
AttributeError: _Feature instance has no attribute '__len__'

Please provide any additional information below
When commenting out the line 'from future import print_function'
and restarting the IPython-console the behavior is as expected - no crash.

Versions and main components

• Spyder Version: 3.2.0
• Python Version: 2.7.13 64 bits
• Qt Version: 4.8.7
• PyQt Version: 4.11.4
• Operating system: Windows

Dependencies

Please go to the menu entry Help > Optional Dependencies (or
Help > Dependencies), press the button Copy to clipboard
and paste the contents below:
IPython >=4.0;<6.0: 5.4.1 (OK)
cython >=0.21 : None (NOK)
jedi >=0.9.0 : 0.10.2 (OK)
nbconvert >=4.0 : 5.2.1 (OK)
numpy >=1.7 : 1.12.0 (OK)
pandas >=0.13.1 : None (NOK)
pycodestyle >=2.3 : 2.3.1 (OK)
pyflakes >=0.5.0 : 1.5.0 (OK)
pygments >=2.0 : 2.2.0 (OK)
pylint >=0.25 : 1.7.2 (OK)
qtconsole >=4.2.0 : 4.3.0 (OK)
rope >=0.9.4 : 0.10.5 (OK)
sphinx >=0.6.6 : 1.6.3 (OK)
sympy >=0.7.3 : None (NOK)

[ccordoba12]

@AxelMKlein, thanks for reporting. We'll fix this error in our 3.2.1 version.

@dalthviz, the fix for this one is quite simple: please remove the TypeError exception of the _get_len method present in SpyderKernel.

Let's also take the opportunity to remove AttributeError from _get_array_shape and _get_array_ndim to avoid similar errors in the future.