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Re: IDL to Python bridge and "file-like" Python object [message #93249 is a reply to message #93245]

Thu, 19 May 2016 11:22

Jim Pendleton
Messages: 165
Registered: November 2011

Senior Member

On Thursday, May 19, 2016 at 5:39:55 AM UTC-6, alx wrote:
> Le jeudi 19 mai 2016 11:53:19 UTC+2, Fabien a écrit :
>> On 05/18/2016 06:22 PM, alx wrote:
>>> Of course, as you said, it is possible to cast the bytes variable inside Python, then to transfer it to IDL. But it is a bit laborious (and slow ?).
>>
>> Does your package support python3? It seems that the bytarray problems
>> has something to do with str representations in legacy python.
>>
>> Cheers,
>>
>> Fabien
>
> I am using FDB 1.6, Python 3.4 (both quoted as compatible) and IDL 8.5.1.
> From my previous post you can check that the FDB blobReader output is a binary bytearray (bytes) within Python, but a string within IDL.
> Therefore, the issue looks like to not come from Python but from the IDL/Python bridge, which (incorrectly, I guess) converts Python bytes variable into IDL string (as you can see in the Exelis Python bridge documentation).
> This choice is unfortunate because Python bytes variable (afaik, but I am not familiar enough with Python) can contain zero values.
> alain.

I assume the actual numeric values stored in the blob are not bytes, but are integers, floats, etc.

In this case, you might need to use a utility like Python's struct to reconstitute your data appropriately. Even if you were to get the data into IDL as a BYTARR() you would still need to perform a conversion to INTEGER, FLOAT, etc., AND concern yourself with endianness.

You may be better off by simply letting the existing Python tools do that work for you first.

This reference may be of use, or there may be better solutions:

https://docs.python.org/2/library/struct.html

Jim P.

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[Message index]

		IDL to Python bridge and "file-like" Python object By: lecacheux.alain on Tue, 17 May 2016 06:54
		Re: IDL to Python bridge and "file-like" Python object By: lecacheux.alain on Wed, 18 May 2016 03:58
		Re: IDL to Python bridge and "file-like" Python object By: Jim Pendleton on Wed, 18 May 2016 06:15
		Re: IDL to Python bridge and "file-like" Python object By: lecacheux.alain on Wed, 18 May 2016 09:22
		Re: IDL to Python bridge and "file-like" Python object By: Fabzi on Thu, 19 May 2016 02:53
		Re: IDL to Python bridge and "file-like" Python object By: lecacheux.alain on Thu, 19 May 2016 04:39
		Re: IDL to Python bridge and "file-like" Python object By: Jim Pendleton on Thu, 19 May 2016 11:22
		Re: IDL to Python bridge and "file-like" Python object By: lecacheux.alain on Thu, 19 May 2016 13:34

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