Github user sanjaydasgupta commented on the issue:
https://github.com/apache/zeppelin/pull/2502
Digging a little deeper to clarify the conflict ... The class
`BaseZeppelinContext` uses two different key-value repositories for two
different needs:
1. **Storage of user-provided inputs entered into dynamic form fields**.
These are held in an `AngularObjectRegistry` associated with the particular
interpreter in effect, and are managed either (a) programmatically by the
functions `z.angularBind(...)` and `z.angularUnbind(...)`, or (b) by using the
`${ ... }` notation described at the link you provided (text-input-form) --
this second option is the one that seems to be (but in fact is not) in conflict
with the substitution proposal described here.
2. **Programmatically assigned data intended to be shared across
interpreters** (currently Spark, R, and Python). These are held in a
`ResourcePool`, and are managed by the functions `z.put(...)`, and
`z.get(...)`. This pull request seeks to substitute values from a
`ResourcePool` into `{ ... }` patterns in interpreter commands.
So, as described above, these are two different facilities, and use similar
but different substitution patterns: the dynamic-forms facility uses `${ ... }`
while this pull request (inter-interpreter data sharing facility) proposes to
use `{ ... }` and `{{ ... }}` (for escaping the basic substitution pattern).
The Jupyter Python examples quoted are drawn from the context of shell
commands spawned by prefixing a command with `!` operator. In this case the {
... } pattern can be used to embed Python snippets (not just a variable name)
into the command, and `{{ ... }}` is used for escaping the `{ ... }`
substitution pattern.
I hope this clarifies the two patterns and uses.
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