Github user mattf-horton commented on the issue:
https://github.com/apache/metron/pull/687
As a professed language nut, when you mention the word "variable", I think
"scope". And it seems to me that by placing the responsibility for variable
assignment/update in the VariableResolver, you've actually tied into a very
natural definition of scope given the way MapVariableResolver already works in
association with a target dictionary or stack of dictionaries.
A. I think you should explicitly discuss scope in the documentation. There
are several scopes already being used in practice, and I think users need to
understand how it all works together, otherwise they will misunderstand and be
bewildered. I am, no doubt, a good example, so dense that I have to ask the
questions below :-)
B. I don't understand why you don't go ahead and enable update in
MapVariableResolver, since IIRC that's the resolver for essentially everything
interesting that uses variables in Stellar.
C. Do I understand correctly from the patch, that variable assignment IS
enabled in lambda expressions? Presumably the scope will be the same instance
dictionary where the input variables are stored, thus making them local,
correct? Can new variables be created as well as input variables be updated?
D. The following scopes come to mind, with associated need for
clarification:
- Lambdas save their input variables in their ephemeral instance context,
initialized by call syntax.
- Comment: questions already asked above
- The REPL used one global dict for scope of its variables, defined by
':='.
- Comment: If I understand correctly, when in the REPL, '=' and ':='
assignments will go to the same global context dictionary, is that correct?
- Profilers, transformations, and several other xml-defined Stellar-using
features, have a persistent instance context, with variables initialized and
updated via an xml syntax.
- Comment: Apparently here we've specifically exclude assignment, even
though this seems to be where it's needed most. Why is that? The instance
context seems ready-made for local variables.
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