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Diffstat (limited to 'vendor/clap/src/_tutorial/chapter_3.rs')
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diff --git a/vendor/clap/src/_tutorial/chapter_3.rs b/vendor/clap/src/_tutorial/chapter_3.rs new file mode 100644 index 0000000..6dc7db2 --- /dev/null +++ b/vendor/clap/src/_tutorial/chapter_3.rs @@ -0,0 +1,84 @@ +//! ## Validation +//! +//! 1. [Enumerated values](#enumerated-values) +//! 2. [Validated values](#validated-values) +//! 3. [Argument Relations](#argument-relations) +//! 4. [Custom Validation](#custom-validation) +//! +//! An appropriate default parser/validator will be selected for the field's type. See +//! [`value_parser!`][crate::value_parser!] for more details. +//! +//! ### Enumerated values +//! +//! If you have arguments of specific values you want to test for, you can use the +//! [`PossibleValuesParser`][crate::builder::PossibleValuesParser] or [`Arg::value_parser(["val1", +//! ...])`][crate::Arg::value_parser] for short. +//! +//! This allows you specify the valid values for that argument. If the user does not use one of +//! those specific values, they will receive a graceful exit with error message informing them +//! of the mistake, and what the possible valid values are +//! +//! ```rust +#![doc = include_str!("../../examples/tutorial_builder/04_01_possible.rs")] +//! ``` +#![doc = include_str!("../../examples/tutorial_builder/04_01_possible.md")] +//! +//! When enabling the [`derive` feature][crate::_features], you can use +//! [`ValueEnum`][crate::ValueEnum] to take care of the boiler plate for you, giving the same +//! results. +//! +//! ```rust +#![doc = include_str!("../../examples/tutorial_builder/04_01_enum.rs")] +//! ``` +#![doc = include_str!("../../examples/tutorial_builder/04_01_enum.md")] +//! +//! ### Validated values +//! +//! More generally, you can validate and parse into any data type with [`Arg::value_parser`]. +//! +//! ```rust +#![doc = include_str!("../../examples/tutorial_builder/04_02_parse.rs")] +//! ``` +#![doc = include_str!("../../examples/tutorial_builder/04_02_parse.md")] +//! +//! A [custom parser][TypedValueParser] can be used to improve the error messages or provide additional validation: +//! +//! ```rust +#![doc = include_str!("../../examples/tutorial_builder/04_02_validate.rs")] +//! ``` +#![doc = include_str!("../../examples/tutorial_builder/04_02_validate.md")] +//! +//! See [`Arg::value_parser`][crate::Arg::value_parser] for more details. +//! +//! ### Argument Relations +//! +//! You can declare dependencies or conflicts between [`Arg`][crate::Arg]s or even +//! [`ArgGroup`][crate::ArgGroup]s. +//! +//! [`ArgGroup`][crate::ArgGroup]s make it easier to declare relations instead of having to list +//! each individually, or when you want a rule to apply "any but not all" arguments. +//! +//! Perhaps the most common use of [`ArgGroup`][crate::ArgGroup]s is to require one and *only* one +//! argument to be present out of a given set. Imagine that you had multiple arguments, and you +//! want one of them to be required, but making all of them required isn't feasible because perhaps +//! they conflict with each other. +//! +//! ```rust +#![doc = include_str!("../../examples/tutorial_builder/04_03_relations.rs")] +//! ``` +#![doc = include_str!("../../examples/tutorial_builder/04_03_relations.md")] +//! +//! ### Custom Validation +//! +//! As a last resort, you can create custom errors with the basics of clap's formatting. +//! +//! ```rust +#![doc = include_str!("../../examples/tutorial_builder/04_04_custom.rs")] +//! ``` +#![doc = include_str!("../../examples/tutorial_builder/04_04_custom.md")] +#![allow(unused_imports)] +use crate::builder::*; + +pub use super::chapter_2 as previous; +pub use super::chapter_4 as next; +pub use crate::_tutorial as table_of_contents; |