Fix IDS uEye support in UC480 driver

[natezb]

After switching to NiceLib for this driver, we're currently only searching for the Thorlabs version of the header (uc480.h), not the IDS version (uEye.h). I think it's reasonable to implement support for multiple sets of possible headers within NiceLib, just as multiple possible lib binaries are supported.

[eedm]

I havent tried Instrumental since the addition of NiceLib but after cloning the latest version my script for using the Thorlabs CMOS camera (IDS uEye) fails as follows:

from instrumental.drivers.cameras.uc480 import UC480_Camera,list_instruments

error Traceback (most recent call last)
in ()
----> 1 from instrumental.drivers.cameras.uc480 import UC480_Camera,list_instruments

C:\Anaconda3\lib\site-packages\instrumental_lib-0.4.dev0-py3.6.egg\instrumental\drivers\cameras\uc480.py in ()
78
79
---> 80 class NiceUC480(NiceLib):
81 info = info
82 prefix = ('is', 'IS')

C:\Anaconda3\lib\site-packages\nicelib-0.4.dev1-py3.6.egg\nicelib\nicelib.py in new(metacls, clsname, bases, classdict)
606 for name in dir(lib):
607 try:
--> 608 attr = getattr(lib, name)
609 if ffi and isinstance(attr, ffi.CData) and ffi.typeof(attr).kind != 'function':
610 dir_lib.append(name)

error: symbol 'is_PersistentMemory' not found in library 'C:\Windows\system32\uc480_64.dll': error 0x7f

[natezb]

@eedm thanks for the report! This is an interesting error, because several things appear to be going on. As the error suggests, your DLL is missing is_PersistentMemory. However, NiceLib is supposed ignore this issue by catching the AttributeError. This isn't working for you because cffi is raising an FFIError instead (I think this changed between versions of cffi at some point). Commit mabuchilab/NiceLib@7ed5fe9 should hopefully fix this for you, so please give it a try if you get a chance.

What's odd is that this means your header does not match the library you have installed. If I recall correctly, you were using the IDS uEye DLLs before, yet I see that NiceLib is accessing uc480_64.dll. So it could be that it's using a uEye header with an older version of the uc480 lib. It appears that is_PersistentMemory was only added to the API this past January.