[issue45987] os.chdir in unittest's test case causes RecursionError on Windows

[Toshihiro Kamiya]

New submission from Toshihiro Kamiya :

When I was writing unit tests, I noticed that os.chdir in the unittest test 
case failed with RecursionError.

It seems to work fine on Ubuntu 20.04, but fails on Windows 10 (might fail on 
macOS).

The attached file is a minimal code to reproduce this.

When I run it, I got an error message as follows

```
PS C:\Users\toshihiro\tmp> python .\test_chdir_fails.py
Traceback (most recent call last):
  File "C:\Users\toshihiro\tmp\test_chdir_fails.py", line 11, in 
unittest.main()
  File 
"C:\Users\toshihiro\AppData\Local\Programs\Python\Python39\lib\unittest\main.py",
 line 101, in __init__
self.runTests()
(snip)
  File 
"C:\Users\toshihiro\AppData\Local\Programs\Python\Python39\lib\traceback.py", 
line 493, in __init__
context = TracebackException(
  [Previous line repeated 487 more times]
RecursionError: maximum recursion depth exceeded
PS C:\Users\toshihiro\tmp>
```

The version of python was:
Python 3.9.5 (tags/v3.9.5:0a7dcbd, May  3 2021, 17:27:52) [MSC v.1928 64 bit 
(AMD64)] on win32

Regards,

--
components: Library (Lib)
files: test_chdir_fails.py
messages: 407711
nosy: tos-kamiya
priority: normal
severity: normal
status: open
title: os.chdir in unittest's test case causes RecursionError on Windows
type: crash
versions: Python 3.9
Added file: https://bugs.python.org/file50476/test_chdir_fails.py

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[issue45987] os.chdir in unittest's test case causes RecursionError on Windows

[Toshihiro Kamiya]

Toshihiro Kamiya  added the comment:

Sorry, the "(snip)" means that it was omitted because it was too long.
I' ll attach a screenshot.

--
Added file: https://bugs.python.org/file50477/FF2dfQ_acAc497b.png

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[issue45987] os.chdir in unittest's test case causes RecursionError on Windows

[Toshihiro Kamiya]

Toshihiro Kamiya  added the comment:

Thank you, eryksun, for pointing out the cause of the problem. I have modified 
the test script and it can now be run on Windows.

The attached file is a revised version of the reproduction script, which 
reflects the modifications made to the test script to prevent the error.

--
resolution:  -> not a bug
stage:  -> resolved
status: open -> closed
Added file: https://bugs.python.org/file50478/test_chdir_wo_fail.py

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[issue45987] os.chdir in unittest's test case causes RecursionError on Windows

[Toshihiro Kamiya]

Toshihiro Kamiya  added the comment:

I think it may be difficult to understand the error message that deleting a 
directory causes "RecursionError or stack overflow", though.

I hope the issue reported as msg377358 will be resolved in some way.

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[issue6830] Some uniformness in defaultdict

[Toshihiro Kamiya]

New submission from Toshihiro Kamiya :

I found the syntax of collections.defaultdict is confusing, at least to 
me.

When I need a defaultdict of int, that is, a defaultdict which contains 
int objects, I can write simply:
a = defaultdict(int)

However, when I want a defaultdict of defaultdict of something, I can't 
write:
d = defaultdict(defaultdict(int))

This raises TypeError.

I understand the argument of defaultdict is not a type (or class), but 
a factory by definition. So I should to write:
d = defaultdict(lambda: defaultdict(int))

But this syntax is somehow confusing to me.
Am I missing some important feature of defaultdict?

The workaround that I've found is:

import collections
class __Helper(object):
  def __getitem__(self, ctor):
return lambda: collections.defaultdict(lambda: ctor())
genericdefaultdict = __Helper()

This helper introduce some generics flavor in defaultdict.
The above cases can be spelt out:

a = genericdefaultdict[int]()
d = genericdefaultdict[genericdefaultdict[int]]()

--
components: Library (Lib)
files: ddh.py
messages: 92193
nosy: t-kamiya
severity: normal
status: open
title: Some uniformness in defaultdict
type: feature request
versions: Python 2.6
Added file: http://bugs.python.org/file14824/ddh.py

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[issue5778] sys.version format differs between MSC and GCC

[Toshihiro Kamiya]

New submission from Toshihiro Kamiya :

The value of sys.version includes a new-line char in GCC build.
'2.5.2 (r252:60911, Oct  5 2008, 19:24:49) \n[GCC 4.3.2]'

MSC build doesn't.
'2.6.2 (r262:71605, Apr 14 2009, 22:46:50) [MSC v.1500 64 bit (AMD64)]'

This seems a kind of pitfall for the developers who use this variable.

--
components: Build
messages: 86060
nosy: t-kamiya
severity: normal
status: open
title: sys.version format differs between MSC and GCC
versions: Python 2.5

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