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Diffstat (limited to 'vendor/clap/src/_derive/_tutorial/chapter_3.rs')
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diff --git a/vendor/clap/src/_derive/_tutorial/chapter_3.rs b/vendor/clap/src/_derive/_tutorial/chapter_3.rs new file mode 100644 index 000000000..16004fcdc --- /dev/null +++ b/vendor/clap/src/_derive/_tutorial/chapter_3.rs @@ -0,0 +1,78 @@ +//! ## 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 +//! +//! For example, if you have arguments of specific values you want to test for, you can derive +//! [`ValueEnum`][super#valueenum-attributes] +//! (any [`PossibleValue`] builder function can be used as a `#[value]` attribute on enum variants). +//! +//! 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_derive/04_01_enum.rs")] +//! ``` +#![doc = include_str!("../../../examples/tutorial_derive/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_derive/04_02_parse.rs")] +//! ``` +#![doc = include_str!("../../../examples/tutorial_derive/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_derive/04_02_validate.rs")] +//! ``` +#![doc = include_str!("../../../examples/tutorial_derive/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. +//! +//! [`ArgGroup`][crate::ArgGroup]s are automatically created for a `struct` with its +//! [`ArgGroup::id`][crate::ArgGroup::id] being the struct's name. +//! +//! ```rust +#![doc = include_str!("../../../examples/tutorial_derive/04_03_relations.rs")] +//! ``` +#![doc = include_str!("../../../examples/tutorial_derive/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_derive/04_04_custom.rs")] +//! ``` +#![doc = include_str!("../../../examples/tutorial_derive/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; |