On 16/09/2023 01:14, Chris Angelico wrote:
But if that tool can be taught that nameof indicates a variable name,
then it can rename inside it just like it would rename anything else.
It works already with existing tools that will treat "nameof(a+b)" as a
function call, which it is syntactically but not semantically, so
renaming b to c will now produce the string "a+c". I think my IDE does
offer to do this with variable names in strings and comments, but it
produces so many false hits I don't enjoy using the feature.
Your problem here is a limitation of the variable renaming tool. I'm
suggesting a solution to that problem. This is not a language problem,
it's an editor problem, so it needs an editor solution.
It needs language (parser) support because it does what you identified
early on: "take whatever is given and put it in quotes", where "whatever
is given" is the text of the expression only available at run-time.
(Actually, I can think of something complicated one might possibly do
with the text produced in exceptions, but please don't.)
Taking an example from my REPL just now (it happens that r2 is the AST
of an Expression), you could simulate nameof with f-strings:
>>> f"{r2.body.op.test=}"
'r2.body.op.test=42'
>>> f"{r2.body.op.test=}".split('=')[0]
'r2.body.op.test'
This also evaluates the expression, encodes the result as text then
discards it, which is undesirable. The point is that renaming r2, or the
fields of a BinOp (if it were project-local, not a stdlib object) would
cause the string to change in most existing IDEs.
Attempts to guess the name from the expression at runtime are futile and
a red herring. Trying to describe the desired semantics that way leads
to nonsensical ideas, I agree.
I'm not convinced this feature is widely useful. Here I'm just trying to
focus us on the *viable* semantics MRAB identified.
--
Jeff Allen
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