[core] Add argument parents by forfudan · Pull Request #25 · forfudan/argmojo

forfudan · 2026-03-12T15:06:52Z

This PR adds an argparse-style “parents” capability to ArgMojo so commands can reuse a shared set of argument definitions and constraint groups, with accompanying documentation and project-metadata updates.

Changes:

Add Command.add_parent(parent) to copy arguments + constraint groups from another Command.
Document the feature in the user manual and cross-library reference table; update planning/changelog.
Extend the pixi run test task to include a new parents test file; update .gitignore.

Copilot

Pull request overview

Adds an argparse-style “parents” capability to ArgMojo so commands can reuse a shared set of argument definitions and constraint groups, with accompanying documentation and project-metadata updates.

Changes:

Add Command.add_parent(parent) to copy arguments + constraint groups from another Command.
Document the feature in the user manual and cross-library reference table; update planning/changelog.
Extend the pixi run test task to include a new parents test file; update .gitignore.

Reviewed changes

Copilot reviewed 6 out of 7 changed files in this pull request and generated 7 comments.

Show a summary per file

File	Description
src/argmojo/command.mojo	Introduces `add_parent()` implementation and its docstring.
pixi.toml	Adds `tests/test_parents.mojo` to the test task.
docs/user_manual.md	Adds a new “Argument Parents …” section + TOC + method reference row.
docs/changelog.md	Adds unreleased changelog entry for argument parents and mentions new tests.
docs/argmojo_overall_planning.md	Marks feature as done and lists `test_parents.mojo` in repo structure.
README.md	Small wording tweak about pre-1.0 stability.
.gitignore	Adds ignore patterns for local `test.mojo` / `test.py`.

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Copilot · 2026-03-12T15:12:58Z

docs/user_manual.md

 $ ./login --user alice --token secret --region eu
 ```

+## Argument Parents and inheritance


Section title uses inconsistent capitalization (“Argument Parents and inheritance”) compared to the rest of the manual’s Title Case headings. Consider renaming to “Argument Parents and Inheritance” (and updating the TOC entry/anchor accordingly) for consistency.

Suggested change

## Argument Parents and inheritance

## Argument Parents and Inheritance

Copilot · 2026-03-12T15:12:59Z

src/argmojo/command.mojo

+            .choice["json"]()
+            .choice["yaml"]()
+        )
+        shared.mutually_exclusive(["json_output", "yaml_output"])


add_parent() docstring example calls shared.mutually_exclusive(["json_output", "yaml_output"]), but neither argument is defined in the example. Since group constraints are validated at registration time, this example would raise immediately; please update it to reference registered argument names or remove the line.

Suggested change

shared.mutually_exclusive(["json_output", "yaml_output"])

Copilot · 2026-03-12T15:12:59Z

src/argmojo/command.mojo

            self.subcommands.append(h^)
        self.subcommands.append(sub^)

+    fn add_parent(mut self, parent: Command) raises:


add_parent takes parent: Command by value. Since Command.__copyinit__ performs a deep copy, passing an existing parent variable will allocate/copy its args/groups/subcommands even though this method only needs read access. Consider taking parent: borrowed Command (or otherwise avoiding a full copy) to prevent unnecessary work for large parent definitions.

Suggested change

fn add_parent(mut self, parent: Command) raises:

fn add_parent(mut self, parent: borrowed Command) raises:

Copilot · 2026-03-12T15:12:59Z

src/argmojo/command.mojo

+        for i in range(len(parent.args)):
+            self.add_argument(parent.args[i].copy())
+        for i in range(len(parent._exclusive_groups)):
+            self._exclusive_groups.append(parent._exclusive_groups[i].copy())
+        for i in range(len(parent._required_groups)):
+            self._required_groups.append(parent._required_groups[i].copy())
+        for i in range(len(parent._one_required_groups)):
+            self._one_required_groups.append(
+                parent._one_required_groups[i].copy()
+            )
+        for i in range(len(parent._conditional_reqs)):
+            self._conditional_reqs.append(parent._conditional_reqs[i].copy())
+        for i in range(len(parent._implications)):
+            self._implications.append(parent._implications[i].copy())
+


add_parent() mutates self incrementally: it appends inherited args one-by-one and then appends inherited constraint groups. If an inherited argument fails add_argument() validation (e.g., name/short/long conflict with an existing child arg), the method will raise after partially modifying self, leaving a subset of parent args added and no constraints copied yet. Consider preflight validation (detect conflicts up front) or staging changes in temporaries and only committing them once all inherited args/groups are known to succeed.

Suggested change

for i in range(len(parent.args)):

self.add_argument(parent.args[i].copy())

for i in range(len(parent._exclusive_groups)):

self._exclusive_groups.append(parent._exclusive_groups[i].copy())

for i in range(len(parent._required_groups)):

self._required_groups.append(parent._required_groups[i].copy())

for i in range(len(parent._one_required_groups)):

self._one_required_groups.append(

parent._one_required_groups[i].copy()

)

for i in range(len(parent._conditional_reqs)):

self._conditional_reqs.append(parent._conditional_reqs[i].copy())

for i in range(len(parent._implications)):

self._implications.append(parent._implications[i].copy())

# Perform inheritance on a temporary copy of `self` so that

# validation failures (e.g. in `add_argument`) do not leave this

# command in a partially updated state.

var tmp = self.copy()

# First, try to add all inherited arguments to the temporary command.

for i in range(len(parent.args)):

tmp.add_argument(parent.args[i].copy())

# If argument addition succeeded, copy over all constraint groups.

for i in range(len(parent._exclusive_groups)):

tmp._exclusive_groups.append(parent._exclusive_groups[i].copy())

for i in range(len(parent._required_groups)):

tmp._required_groups.append(parent._required_groups[i].copy())

for i in range(len(parent._one_required_groups)):

tmp._one_required_groups.append(

parent._one_required_groups[i].copy()

)

for i in range(len(parent._conditional_reqs)):

tmp._conditional_reqs.append(

parent._conditional_reqs[i].copy()

)

for i in range(len(parent._implications)):

tmp._implications.append(parent._implications[i].copy())

# All operations succeeded; commit the staged changes back to `self`.

self.args = tmp.args

self._exclusive_groups = tmp._exclusive_groups

self._required_groups = tmp._required_groups

self._one_required_groups = tmp._one_required_groups

self._conditional_reqs = tmp._conditional_reqs

self._implications = tmp._implications

Copilot · 2026-03-12T15:13:00Z

pixi.toml

+    && mojo run -I src -D ASSERT=all tests/test_prompt.mojo < /dev/null \
+    && mojo run -I src -D ASSERT=all tests/test_parents.mojo"""


The test task now runs tests/test_parents.mojo, but that file is not present in the repository. As written, pixi run test will fail; either add/commit the new test file or remove this invocation.

Suggested change

&& mojo run -I src -D ASSERT=all tests/test_prompt.mojo < /dev/null \

&& mojo run -I src -D ASSERT=all tests/test_parents.mojo"""

&& mojo run -I src -D ASSERT=all tests/test_prompt.mojo < /dev/null"""

Copilot · 2026-03-12T15:13:00Z

docs/changelog.md

 - Add Developer Validation section to user manual documenting the two-layer validation model (compile-time `StringLiteral` + runtime registration-time `raises`) with recommended workflow (PR #22).
 - Add `pixi run debug` task that runs all examples under `-D ASSERT=all` with `--help` to exercise registration-time validation in CI (PR #22).
 - Add `tests/test_prompt.mojo` with tests covering interactive prompting builder methods, optional/required prompt arguments, prompting skipped when values are provided, choices and defaults integration, field propagation through copy, and combined features (PR #23).
+- Add `tests/test_parents.mojo` with 20 tests covering argument parents: basic flag/value/positional/default inheritance, short flags, multiple parents, child-own args coexistence, group constraint inheritance (mutually exclusive, required together, one-required, conditional, implications), parent shared across children, count/append/range argument inheritance, empty parent, parent immutability, and parent with subcommands (PR #25).


The changelog claims tests/test_parents.mojo was added, but the file is not present in the repo. Please either include/commit the new test file or adjust this entry so the changelog matches what was actually added.

Suggested change

- Add `tests/test_parents.mojo` with 20 tests covering argument parents: basic flag/value/positional/default inheritance, short flags, multiple parents, child-own args coexistence, group constraint inheritance (mutually exclusive, required together, one-required, conditional, implications), parent shared across children, count/append/range argument inheritance, empty parent, parent immutability, and parent with subcommands (PR #25).

- Add tests covering argument parents: 20 tests covering basic flag/value/positional/default inheritance, short flags, multiple parents, child-own args coexistence, group constraint inheritance (mutually exclusive, required together, one-required, conditional, implications), parent shared across children, count/append/range argument inheritance, empty parent, parent immutability, and parent with subcommands (PR #25).

Copilot · 2026-03-12T15:13:00Z

docs/argmojo_overall_planning.md

+├── test_prompt.mojo               # interactive prompting tests
+└── test_parents.mojo              # argument parents (shared definitions) tests


This repository-structure section lists tests/test_parents.mojo, but that file does not exist in the repo. Please add/commit the test file or update the documented tree so it stays accurate.

Suggested change

├── test_prompt.mojo # interactive prompting tests

└── test_parents.mojo # argument parents (shared definitions) tests

└── test_prompt.mojo # interactive prompting tests

- Fix title capitalization: 'Argument Parents and inheritance' → 'Argument Parents and Inheritance' (TOC + heading) - Remove incorrect docstring example (mutually_exclusive with undefined argument names) - Make add_parent() atomic: rollback partially-added args on failure so self is never left in a half-inherited state

forfudan requested a review from Copilot March 12, 2026 15:06

Copilot started reviewing on behalf of forfudan March 12, 2026 15:07 View session

Copilot AI reviewed Mar 12, 2026

View reviewed changes

Add parent arguments

e418cb2

forfudan force-pushed the update branch from 47e4c9f to e418cb2 Compare March 12, 2026 16:02

forfudan merged commit 10da0cf into main Mar 12, 2026
2 checks passed

forfudan deleted the update branch March 12, 2026 17:23

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[core] Add argument parents#25

[core] Add argument parents#25
forfudan merged 2 commits intomainfrom
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forfudan commented Mar 12, 2026 •

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	## Argument Parents and inheritance
	## Argument Parents and Inheritance

	fn add_parent(mut self, parent: Command) raises:
	fn add_parent(mut self, parent: borrowed Command) raises:

		&& mojo run -I src -D ASSERT=all tests/test_prompt.mojo < /dev/null \
		&& mojo run -I src -D ASSERT=all tests/test_parents.mojo"""

		├── test_prompt.mojo # interactive prompting tests
		└── test_parents.mojo # argument parents (shared definitions) tests

	├── test_prompt.mojo # interactive prompting tests
	└── test_parents.mojo # argument parents (shared definitions) tests
	└── test_prompt.mojo # interactive prompting tests

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forfudan commented Mar 12, 2026 •

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