feat: add flag action

[kooksee]

This pull request introduces several improvements and enhancements to the command-line framework, focusing on option handling, flag actions, and code clarity. The most significant changes include the addition of support for per-flag Action callbacks, improvements to global flag detection, and minor demo adjustments.

Option/Flag Handling Improvements

• Added an Action field to the Option struct, allowing you to specify a callback that runs after a flag is parsed and set. If the callback returns an error, command execution is halted. (option.go)
• Updated the command invocation flow to execute Action callbacks for all set options, ensuring each action is only run once per flag and prioritizing the most specific (child) command's action if a flag is overridden. Actions are not run if help is requested. (command.go)

Global Flag Logic

• Simplified and clarified the logic for determining global flags: now all non-hidden options in the root command are considered global flags, rather than relying on a hardcoded list. (command.go)

Middleware Chain Refactoring

• Refactored the middleware chain construction loop for clarity and consistency, ensuring the correct execution order of middleware from root to child command. (command.go)

Demo and Example Adjustments

• Updated the demo example to use a string flag instead of a boolean for the upper option, and added a shorthand flag. (example/demo/main.go) [1] [2]

Version Bump

• Bumped the version from v0.0.3 to v0.0.4. (.version/VERSION)

[gemini-code-assist]

Summary of Changes

Hello @kooksee, I'm Gemini Code Assist¹! I'm currently reviewing this pull request and will post my feedback shortly. In the meantime, here's a summary to help you and other reviewers quickly get up to speed!

This pull request introduces a significant enhancement to the command-line argument parsing system by adding a new 'Action' callback mechanism for flags. This allows for custom logic, validation, or side effects to be performed immediately after a flag's value is set, providing greater flexibility in handling command-line inputs. Additionally, the logic for identifying global flags has been improved for better maintainability and the project version has been updated.

Highlights

• Flag Action Callback: Introduced a new 'Action' field in the 'Option' struct, allowing developers to define custom functions that execute when a flag is parsed and set.
• Action Execution Logic: Implemented the execution of these 'Action' callbacks within the command 'run' function, ensuring they are called for changed flags, respecting flag override order, and handling errors.
• Global Flag Identification: Refined the 'GetGlobalFlags' method to dynamically identify global flags as all non-hidden options present in the root command, rather than a hardcoded list.
• Version Update: The project version has been incremented from 'v0.0.3' to 'v0.0.4'.

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[gemini-code-assist]

Code Review

This pull request introduces a new Action field for options, allowing functions to be executed when a flag is set. The implementation correctly handles flag overrides in command hierarchies and avoids executing actions when help is requested. I've suggested a small refactoring to simplify the action execution logic, making it more idiomatic and efficient. The changes to the example file and version bump are appropriate.

[kooksee]

/gemini 请再次 review

[gemini-code-assist]

Code Review

This pull request introduces a new Action field for options, allowing a callback to be executed when a flag is set. This is a useful feature for custom validation or triggering side effects. The implementation is generally well done, but I've found a critical issue in the execution logic for actions on overridden flags, where the parent's action is incorrectly prioritized over the child's. My review includes a suggested fix that also improves performance by removing an unnecessary allocation.