Registering filters

[The9Cat]

Question: Is there an easy way to register the blosc filter (or any other filter) in HighFive?

BTW, I do hope that the developers will continue to support this project. It's one of the best out there for C++.

[1uc]

The same question was asked here:
https://github.com/BlueBrain/HighFive/pull/980/files

I think it ran out of steam when we also looked at the packaging situation of blosc and blosc2. Solving the packaging is a requirement for testing; and testing is a requirement for supporting a feature.

[The9Cat]

blosc and blosc2 are packaged in my Linux distros these days (e.g. Ubuntu) in both library dev versions and as plugins for HDF5 and h5py.

Just as HighFive doesn't supply HDF5 libraries, it doesn't need to be HighFive's responsibility to supply blosc (e.g. as a submodule).

So how a about an add-on strategy with the support headers that wrap the blosc registering, etc. only installed if the user has libblosc-dev available? Could be part of the initial CMakeLists.txt configuration...

[1uc]

The packaging issue is mostly relevant, because we need to be able to setup CI. The HighFive code itself can live in headers <highfive/blosc{,2}.hpp> and if a users knows they have blosc they include the header.

I've found 3/4 libraries on launchpad:

• c-blosc: https://launchpad.net/ubuntu/+source/c-blosc
• c-blosc2: https://launchpad.net/ubuntu/+source/c-blosc2
• hdf5-blosc: https://launchpad.net/ubuntu/+source/hdf5-blosc

But I'm still short the final library that would allow me to use blosc2 together with HDF5. This time around I could find dedicated source repos for the plugins of each library:

• https://github.com/Blosc/hdf5-blosc/tree/master
• https://github.com/Blosc/HDF5-Blosc2
  (which for blosc2 is much better than what I found last time.)

[The9Cat]

Not 100% sure, but I believe that the hdf5-blosc plugin wraps both blosc and blosc2. I haven't examined the source, but after installing those packages, I can use h5repack with both UD=32001 and UD=32026 and verify a compressed file using h5dump.