[demianw]

What was wrong

EvaluateQueries.visit_Call has a save('name') branch. It has been there since 5cd2746 (2012, "Added outlier rejection and the interactive shell"), but it has never worked:

• it tests isinstance(node.args, ast.Constant), and node.args is a list, so the branch is never taken;
• visit_Expr rejects bare calls before visit_Call is reached.

On master, a |= 1 / save('a') fails with Invalid expression at line: 2.

What save was meant to do

The CLI writes one output file per name in EvaluateQueries.queries_to_save, which eval_queries returns. A name gets into queries_to_save in two ways:

• name = <query> evaluates the query and adds it;
• a line containing only name adds an already evaluated query.

name |= <query> evaluates the query without adding it, for intermediate results.

The dead branch only did self.queries_to_save.add(<string>). So save('name') was meant to be a third way to request an evaluated query for output. Unlike a bare name, it also works for dotted names: visit_Expr only accepts ast.Name, so cst.left alone on a line is rejected. With save, a query defined as cst.side |= ... can be written with save('cst.left').

Change (option A: fix, this PR)

• Remove the dead branch from visit_Call.
• In visit_Expr, accept save('<name>') (exactly one string argument) next to the bare-name case. It uses the same lookup and the same Query X not known line: N error for unknown names.
• save is only valid as a statement: x = save('a') is still rejected with Invalid query in line N. Names are matched after preprocessing, so they are case-insensitive like everything else in WMQL. Glob patterns are not expanded.

Behaviour change: save('name') lines that used to fail now work. Nothing else changes.

Not changed: in the interactive shell (--interactive), save('a') is now accepted but does not write a file. The shell writes queries through its own SaveQueries visitor and its save <name> command, not through queries_to_save. Writing files from the shell would need about 3 more lines in SaveQueries.visit_Expr.

Option B: remove instead

If you would rather not have a second way to do what a bare name does, the alternative is to delete the six dead lines in visit_Call (the elif ... 'save' branch) and keep save(...) an error. I chose the fix because the semantics are unambiguous from the code (add the name to queries_to_save), it is small, and it fills a real gap: saving dotted |= queries. save is not documented and no packaged .qry file uses it, so either choice is safe.

Testing

• New test_save_query in tract_querier/tests/test_query_eval.py. It checks that A |= 0; B.left |= 1; C |= 0; A; save('B.left') returns exactly {a, b.left}, and that save('B') (unknown query) and X = save('A') raise TractQuerierSyntaxError. It fails on master with Invalid expression at line: 5.
• python -m pytest -q -p no:cacheprovider tract_querier: 43 passed, 1 skipped.

Merge order: touches visit_Call / visit_Expr in query_processor.py, as do #133 (#103: visit_Attribute, visit_For, relative terms) and #139 (#115: the starargs lines in visit_Call). Expect textual conflicts at most.

Closes #104

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