Trait InputCollector

Source

pub trait InputCollector<T>: Send + Sync {
    // Required methods
    fn name(&self) -> &'static str;
    fn is_available(&self, matches: &ArgMatches) -> bool;
    fn collect(&self, matches: &ArgMatches) -> Result<Option<T>, InputError>;

    // Provided methods
    fn validate(&self, _value: &T) -> Result<(), String> { ... }
    fn can_retry(&self) -> bool { ... }
}

Expand description

A source that can collect input of type T.

Input collectors are the building blocks of input chains. Each collector represents one way to obtain input: from CLI arguments, stdin, environment variables, editors, or interactive prompts.

§Implementation Guidelines

is_available should return false if this source cannot provide input in the current environment (e.g., no TTY for prompts, stdin not piped for stdin source).
collect should return Ok(None) to indicate “try the next source” and Ok(Some(value)) when input was successfully collected. Return Err only for actual failures.
Interactive collectors should implement can_retry to return true, allowing validation failures to re-prompt the user.

§Example

use standout_input::{InputCollector, InputError};
use clap::ArgMatches;

struct FixedValue(String);

impl InputCollector<String> for FixedValue {
    fn name(&self) -> &'static str { "fixed" }

    fn is_available(&self, _: &ArgMatches) -> bool { true }

    fn collect(&self, _: &ArgMatches) -> Result<Option<String>, InputError> {
        Ok(Some(self.0.clone()))
    }
}

Required Methods§

Source

fn name(&self) -> &'static str

Human-readable name for this collector.

Used in error messages and debugging. Examples: “argument”, “stdin”, “editor”, “prompt”.

Source

fn is_available(&self, matches: &ArgMatches) -> bool

Check if this collector can provide input in the current environment.

Returns false if:

Interactive collector but no TTY available
Stdin source but stdin is not piped
Argument source but argument was not provided

The chain will skip unavailable collectors and try the next one.

Source

fn collect(&self, matches: &ArgMatches) -> Result<Option<T>, InputError>

Attempt to collect input from this source.

§Returns

Ok(Some(value)) - Input was successfully collected
Ok(None) - This source has no input; try the next one in the chain
Err(e) - Collection failed; abort the chain with this error

Provided Methods§

Source

fn validate(&self, _value: &T) -> Result<(), String>

Validate the collected value.

Called after successful collection. Override to add source-specific validation that can trigger re-prompting for interactive sources.

Default implementation accepts all values.

Source

fn can_retry(&self) -> bool

Whether this collector supports retry on validation failure.

Interactive collectors (prompts, editor) should return true to allow re-prompting when validation fails. Non-interactive sources (args, stdin) should return false.

Default is false.