createMultiTag with a Duplicate name sometimes gives empty RuntimeError: about nixpy

[jgrewe]

Hi Ajay,
unfortunately I cannot reproduce this bug. The following code throws the expected Exception:

import nix
f = nix.File.open('test.h5', nix.FileMode.Overwrite) 
f.create_block('Test', 'test_type')
for i in range(100):
    try:
        f.create_block('Test', 'test_type')
    except Exception, e:
       print(str(i) + ':  ' + str(e))

0: Duplicate name given - names have to be unique for a given entity type & parent. (createBlock)
1: Duplicate name given - names have to be unique for a given entity type & parent. (createBlock)
2: Duplicate name given - names have to be unique for a given entity type & parent. (createBlock)
3: Duplicate name given - names have to be unique for a given entity type & parent. (createBlock)
4: Duplicate name given - names have to be unique for a given entity type & parent. (createBlock)
5: Duplicate name given - names have to be unique for a given entity type & parent. (createBlock)

...

96: Duplicate name given - names have to be unique for a given entity type & parent. (createBlock)
97: Duplicate name given - names have to be unique for a given entity type & parent. (createBlock)
98: Duplicate name given - names have to be unique for a given entity type & parent. (createBlock)
99: Duplicate name given - names have to be unique for a given entity type & parent. (createBlock)

Could you try this out or provide a code snippet that produces the error?

Best,
Jan

[jgrewe]

Ups, at least half of my brain was asleep... However, the same is holds for multi_tags:

 import numpy as np 
 import nix
 f = nix.File.open('test.h5', nix.FileMode.Overwrite)
 x = np.random.randn(1000)
 b = f.create_block('Test', 'test')
 da = b.create_data_array('test', 'test', data=x)
 b.create_multi_tag('test','test_type', da)
 for i in range(100):
    try:
           b.create_multi_tag('test', 'test_type', da)
    except Exception, e:
           print(str(i) + ':  ' + str(e))

gives me 100 correct exceptions.

[balint42]

Yes this I think is correct behaviour. The reason is as written in the message. Or do we misunderstand your problem?

[ajkswamy]

Hello Jan and Balint

Here is a small test class(testFile.py) and test script(testMultipleRuns.py).

https://copy.com/uqN1iXlyIQTR0s7G

It seems that the error message depends on the commands which are run before attempting to add a duplicate-name multitag.

Maybe there is something wrong in the way I am using NIX. If so, I would appeciate your suggestions.

Thanks and Cheers
Ajay

[jgrewe]

Hi Ajay, after some digging I gave up on finding the cause for this problem. On the C++ side, the exceptions are correctly thrown and contain a correct error message. On the python side they sometimes loose their messages.
I created explicit transforms that map the nix::C++ exceptions to python errors. In case of empty messages, a standard error message is provided giving at least an idea what went wrong. (see pull request #119.

Thanks again for your bug report and the code!