Vega: Nest transform generate signal does not update data

[nyurik]

The code in PR seems to indicate that setting generate parameter for the nest transform via a signal does not regenerate the data pipeline.

Repo: open PR's vega code, and click the checkbox. Also try to set the initial value to false, and click the checkbox.

[jheer]

Thanks! I fixed this issue as part of a larger refactoring of hierarchy management and treelink generation. The latest is in master in the vega-hierarchy repo. However, the updates include changes to the parameter signatures of some of the transforms, so I'm batching them for a later Vega release that includes some more significant changes for, among other things, parity with D3 v5.

I'll close this issue once the changes have been released.

[nyurik]

@jheer changes to the parameter signatures means a breaking change for all existing users of Vega graphs. Please make it backward compatible, otherwise we won't be able to use it - imagine breaking tens of thousands of graphs with the upgrade -- noone would get the new version, as the upgrade cost of a big platform instantly skyrockets.

[nyurik]

P.S. Vega could still show a warning when older parameter style is being used, e.g. "param X has been renamed to param Y for trtansform Z, please update your graph". Or just support both names. Thx for all your work on this!

[jheer]

Yes, I'm well aware of the negative effects of non-backwards-compatible changes. Don't worry 😁

[jheer]

Fixed in v4.0.0-rc.1.