[Mne_analysis] [mne-python] strange behavior of raw.save()

[Denis-Alexander Engemann]

Thanks Martin,

that must be it.
I actually I was testing a new command line tool of mine for mass riff
export / augmentation  / conversion
And in one of the use cases I simply wanted to change the info
structure without loading the data.
So this means I can either preload the data or work around it by e.g.
iterative renaming.

To prevent users from tnings like that one could add something like

raw.save(fname)

(...)

if fname == self.raw.info['filename'] and not self.preload:
    raise ValueError("Invalid operation "
                            "Either load data or use alternative file name")


Wdyt?

Cheers,
Denis



2012/9/8 Martin Luessi <mluessi at nmr.mgh.harvard.edu>:
> Hi Denis,
>
> Are you by any chance saving the raw file to the same file from where you
> read it? I.e., something like
>
> raw = Raw('test_raw.fif')
> ..
> raw.save('test_raw.fif')
>
> Unless you use preload=True, this won't work since raw.save() will read from
> the file and at the same time overwrite it. We should add a check such that
> it throws and exception with a explanatory error message if one tries to do
> this.
>
> Martin
>
>
> On 09/08/12 16:04, Denis-Alexander Engemann wrote:
>>
>> Hi all,
>>
>> on saving a raw file using the instance method save() I get the
>> following error message.
>>
>> http://pastebin.com/g66H4svV
>>
>> After that the file is not readable anymore ( the same error message
>> will appear as Raw.__init__() is called. )
>>
>> If I use an alternative file name this does not happen.
>>
>> a) what is the reason for that / what does it actually tell, and
>>
>> b) shouldn't that rather throw an exception than messing up the original
>> file?
>>
>>
>> Cheers,
>> Denis
>>
>>
>>
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