Discussion: should part of Chart Registry move to compat

[kum-deepak]

I see the following types of users:

• Users that simply want to use dc to create a single group of linked charts, they would never create more than one group.
• Users looking to create more than one group of linked charts on a single page.
• SPA users, who would benefit from creating ChartGroup as a local variable.

Based on the above, we should do the following:

• The recommended way of using ChartGroup/Registry.
• Deprecate specific API and move those to the compat layer.

[gordonwoodhull]

Could you spell this out some more? I’m missing the argument.

Also, what is “the specific API”?

[kum-deepak]

For example, if we suggest that users should always create an explicit ChartGroup object (i.e., empty or string argument is not allowed), then entire ChartRegistry and *All functions can move to the compat layer.

Another example, if an empty argument is allowed, but, string argument is not allowed (i.e., if other than default chart group is needed, an instance of ChartGroup must be provided), in that case, a significant part of ChartRegistry and most of *All can be moved to the compat layer.

I have my doubts originating from the fact that ChartRegistry maintains a global state. However, the updated stocks example does need a global state for this purpose.

This whole thing is optional - doing no change is acceptable as well.

[gordonwoodhull]

Thanks! Now I get where you’re going with this.

This is good food for thought. I like the way it gets rid of global state, and I especially like the way that it gets us closer to #988, removing the chart registry in favor of something third-party. (We would have to deprecate the chart registry for a couple of major versions IMO.)

Let’s continue to think about this, and see what other global state there is.

As always, comments from the community are welcome!

[kum-deepak]

There are isolated variables here and there - like uniqueId keeps the last id, events trigger keeps the last event. However, I do not think anything major. I will keep looking closely.

[kum-deepak]

With the recent work with ChartGroup and FilterStorage, I believe we can now move the entire ChartRegistry to the compact layer.

For this, string argument for a group name will not be allowed. The default will be stored in the ChartGroup itself (created on demand). I will do a PR soon.