[masenf]

All Submissions:

• Have you followed the guidelines stated in CONTRIBUTING.md file?
• Have you checked to ensure there aren't any other open Pull Requests for the desired changed?

Type of change

• New feature (non-breaking change which adds functionality)

Description

Adds reflex_base.vars.get_leaf_vars(var) -> Sequence[Var], which returns the vars a var reads, deduplicated in order of first appearance. Each leaf is the object the compound var was built from, so callers can rely on identity.

A var operation such as State.items.filter(...) or State.items[1:] renders to a fresh value every time it is evaluated, so a React hook that reads one cannot list it as a dependency without recomputing on every render. With this helper such a hook can depend on State.items instead:

>>> [str(v) for v in get_leaf_vars((State.a + 1) * State.b)]
['state.a', 'state.b']
>>> [str(v) for v in get_leaf_vars(State.items.filter(lambda item: item == loop_var))]
['state.items', 'loop_var']
>>> [str(v) for v in get_leaf_vars(LiteralVar.create([[memo_prop], f"{State.name}"]))]
['memo_prop', 'state.name']

How a var is taken apart:

• A CustomVarOperation reads its operands; every other cached operation (an array slice, an object item, a string concatenation, a function call) reads what its own fields hold. A raw value among them, such as a call argument or a container item, is converted through LiteralVar.create the way the renderer does, so an f-string with a var inside a list still reads that var.
• A cast reads what it wraps, so a cast around a leaf is the leaf, as the caller holds it: State.x comes back as State.x. A cast around an operation or a function is seen through.
• A literal dissolves: a scalar, Decimal, range or datetime reads nothing, a tuple, list, set or mapping reads what it holds, a color reads its parts, and any other value (an event, a component) stays whole as a leaf, since what it reads is not known.
• A function reads its body minus the names its parameters bind, so a predicate closing over nothing yields no leaf and one closing over a loop var yields that var. It stays whole when a free leaf of its body still mentions a parameter, such as a var built from f"{item}.length" or a nested function closing over item, since hoisting that leaf out would name something bound only inside the function.
• A state field access is a leaf.

A test pins how every CachedVarOperation subclass in reflex_base and reflex is sorted, so a new one has to be placed on purpose rather than falling through unnoticed.

The first use is the data editor rework in #7607, which is stacked on this PR and builds the dependency arrays of its useMemo and useCallback hooks from it.

New Feature Submission:

• Does your submission pass the tests?
• Have you linted your code locally prior to submission?

Changes To Core Features:

• Have you added an explanation of what your changes do and why you'd like us to include them?
• Have you written new tests for your core changes, as applicable?
• Have you successfully ran tests with your changes locally?

Tests in tests/units/reflex_base/vars/test_base.py assert leaf identity and cover a leaf returned alone, literals dissolving (scalars, containers, nested f-strings, colors, an event kept whole), nested operations and casts with deduplication, the operations with their own fields, raw call arguments, function bodies (closures, nested lambdas, rest parameters, a color body, a cast around a function, a body leaf reading a parameter keeping the function whole), and the sorting of every cached operation class. ruff, pyright on the touched files, and pytest tests/units/reflex_base/vars/test_base.py pass on 3.14 and in a separate 3.11 environment.

🤖 Generated with Claude Code

https://claude.ai/code/session_01RqJ6TNt8AXzbDVm5kLb2nD

[greptile-apps]

Confidence Score: 5/5

[Medium impact] No new blocking issue was established in the changes since the previous review.

Summary

Adds get_leaf_vars to collect the inputs behind derived vars for React hook dependencies.

• Callers can find the vars a derived expression reads.

_{Reviews (6) · Last reviewed commit: "feat(vars): keep a function whole when a..." · Reviewed by Greptile}

[cubic-dev-ai]

All reported issues were addressed across 4 files

<sub>Reply with feedback, questions, or to request a fix.

View guided diff | Turn on auto-fix | Re-trigger cubic</sub>

[codspeed]

Merging this PR will not alter performance

⚠️ 14 benchmarks spent significant time in system calls

System calls cannot be consistently instrumented, so they are not included in the measure, which understates the real cost. Please switch to the Walltime instrument to accurately measure system calls.

Measurement and system calls

• test_cli_startup[version]
• test_cli_startup[help]
• test_get_state[memory]
• test_cli_startup[deploy_help]
• test_emit_update
• test_event_queue_dispatch
• test_import_cli
• test_state_manager_memory_warm_get
• test_modify_state[disk]
• test_get_state[disk]
• …and 4 more

✅ 148 untouched benchmarks

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_{Comparing claude/get-leaf-vars (2c6c165) with main (4be8b4d)}

[cubic-dev-ai]

All reported issues were addressed across 3 files (changes from recent commits).

<sub>Reply with feedback, questions, or to request a fix.

View guided diff | Turn on auto-fix | Re-trigger cubic</sub>