perspective v0.6.2

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Here is a list of all the pending dependencies (and their versions) for this repo. Please double check all dependencies before merging.

Name	Upstream Version	Current Version
cmake	3.19.6

Dependency Analysis

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Analysis of the source code shows a discrepancy between the library's imports and the package's stated requirements in the meta.yaml.

Packages found by inspection but not in the meta.yaml:

• pytz
• tornado

[conda-forge-linter]

Hi! This is the friendly automated conda-forge-linting service.

I just wanted to let you know that I linted all conda-recipes in your PR (recipe) and found it was in an excellent condition.

[xhochy]

@conda-forge-admin please rerender

[xhochy]

@conda-forge/perspective This is ready for review.

[timkpaine]

I need to rewrite the meta now that we automatically download and statically link arrow , also need to see if we can expand onto win and Mac now that the build process is a bit more flexible.

[xhochy]

From the Arrow developer perspective: Why do you need to statically include pyarrow in your distribution? Is there anything we can do to avoid that?

With the conda-forge hat: We don't want downloads inside the build. Could we somehow work around this in the conda setting to make the build offline-capable?

[timkpaine]

@xhochy for 1, at the end of the day it became too difficult to link against the arrow shared libraries in a reliable way. E.g. on windows making sure that our dlls could figure out arrow dlls meant either doing runtime nonsense against the hope of ../pyarrow/, or trying to find and copy dlls at build time. Lots of annoying rpath complexity across environments that often broke in virtualenvs. Melding CMake and python extensions is difficult enough without trying to leverage other C++ codebases embedded within other python libraries. A good summary is here: finos/perspective#1290

With this change, the complicated and admittedly brittle code we
have in place to deal with detecting PyArrow's install location,
managing PyArrow versions, copying Arrow DLLs (on Windows),
etc. can be removed, as Perspective's build no longer depends on
the existence and correct versioning of an asset we have little control over.

Additionally, users can install the newest version of PyArrow in order
to gain access to features/fixes without worrying about Perspective
compatibility beyond the binary format, which is expected to remain
stable and compatible between versions. Finally, the developer
experience should be improved for both source builds and configuring
the conda-forge build, which can unpin its PyArrow dependency.

For conda forge, our external dependencies are listed here (everything inside psp_build_dep):
https://github.com/finos/perspective/blob/master/cpp/perspective/CMakeLists.txt#L419

I think we're pretty done with making tweaks to this as is pretty frustrating across environments. If all of these libraries were available within conda forge in a standard way across all operating systems, we could modify the build dep function to first check if they exist already. But at the end of the day, these are all statically linked into the output libraries and only used as completely internally or for transport to/from the corresponding js libraries (as is the case for arrow). Nothing vendored is exposed anywhere externally.

[xhochy]

Thanks for the information and the link 👍 I'm not here to block anything but just collecting feedback about these issues. Linking across Python package boundaries especially outside of conda-controlled environments is quite hard and it seems that every (py)arrow consumer found a different workaround. Hopefully, we can amalgamate that in future into a convenient and reliable solution.

Note that one workaround to do less vendoring on conda-forge but still give your uses a bit of flexibility in their pinnings is to simply build for multiple Arrow versions as we do in https://github.com/conda-forge/snowflake-connector-python-feedstock/blob/e9824ea18f606634ffd152a30d436514a4a7bd5a/recipe/conda_build_config.yaml#L1

[timkpaine]

Thanks for the information and the link 👍 I'm not here to block anything but just collecting feedback about these issues. Linking across Python package boundaries especially outside of conda-controlled environments is quite hard and it seems that every (py)arrow consumer found a different workaround. Hopefully, we can amalgamate that in future into a convenient and reliable solution.

yep definitely

Note that one workaround to do less vendoring on conda-forge but still give your uses a bit of flexibility in their pinnings is to simply build for multiple Arrow versions as we do in https://github.com/conda-forge/snowflake-connector-python-feedstock/blob/e9824ea18f606634ffd152a30d436514a4a7bd5a/recipe/conda_build_config.yaml#L1

Its slightly more tricky (but a lot easier after arrow c stuff and protocol stabilization) because the arrow compiled on the python side must be compatible with the arrow compiled to webassembly on the JS side if you want to use the two together (as in the JupyterLab extension of the standalone examples like this one). But we'll keep this in mind, and I'll take a look at filling in some of the conda gaps on our C++ dependencies so that others can have an easier time.