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authorDaniel Baumann <daniel.baumann@progress-linux.org>2024-04-17 12:03:36 +0000
committerDaniel Baumann <daniel.baumann@progress-linux.org>2024-04-17 12:03:36 +0000
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tree3f66c4a5918660bb8a758ab6cda5ff8ee4f6cdcd /vendor/clap/src/_derive/mod.rs
parentAdding upstream version 1.64.0+dfsg1. (diff)
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Adding upstream version 1.65.0+dfsg1.upstream/1.65.0+dfsg1
Signed-off-by: Daniel Baumann <daniel.baumann@progress-linux.org>
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+//! # Documentation: Derive Reference
+//!
+//! 1. [Overview](#overview)
+//! 2. [Attributes](#attributes)
+//! 1. [Terminology](#terminology)
+//! 2. [Command Attributes](#command-attributes)
+//! 3. [Arg Attributes](#arg-attributes)
+//! 4. [ValueEnum Attributes](#valueenum-attributes)
+//! 5. [Possible Value Attributes](#possible-value-attributes)
+//! 3. [Arg Types](#arg-types)
+//! 4. [Doc Comments](#doc-comments)
+//! 5. [Mixing Builder and Derive APIs](#mixing-builder-and-derive-apis)
+//! 6. [Tips](#tips)
+//!
+//! ## Overview
+//!
+//! To derive `clap` types, you need to enable the [`derive` feature flag][crate::_features].
+//!
+//! Example:
+//! ```rust
+#![doc = include_str!("../../examples/demo.rs")]
+//! ```
+//!
+//! Let's start by breaking down the anatomy of the derive attributes:
+//! ```rust
+//! use clap::{Parser, Args, Subcommand, ValueEnum};
+//!
+//! /// Doc comment
+//! #[derive(Parser)]
+//! #[clap(APP ATTRIBUTE)]
+//! struct Cli {
+//! /// Doc comment
+//! #[clap(ARG ATTRIBUTE)]
+//! field: UserType,
+//!
+//! #[clap(value_enum, ARG ATTRIBUTE...)]
+//! field: EnumValues,
+//!
+//! #[clap(flatten)]
+//! delegate: Struct,
+//!
+//! #[clap(subcommand)]
+//! command: Command,
+//! }
+//!
+//! /// Doc comment
+//! #[derive(Args)]
+//! #[clap(PARENT APP ATTRIBUTE)]
+//! struct Struct {
+//! /// Doc comment
+//! #[clap(ARG ATTRIBUTE)]
+//! field: UserType,
+//! }
+//!
+//! /// Doc comment
+//! #[derive(Subcommand)]
+//! #[clap(PARENT APP ATTRIBUTE)]
+//! enum Command {
+//! /// Doc comment
+//! #[clap(APP ATTRIBUTE)]
+//! Variant1(Struct),
+//!
+//! /// Doc comment
+//! #[clap(APP ATTRIBUTE)]
+//! Variant2 {
+//! /// Doc comment
+//! #[clap(ARG ATTRIBUTE)]
+//! field: UserType,
+//! }
+//! }
+//!
+//! /// Doc comment
+//! #[derive(ValueEnum)]
+//! #[clap(VALUE ENUM ATTRIBUTE)]
+//! enum EnumValues {
+//! /// Doc comment
+//! #[clap(POSSIBLE VALUE ATTRIBUTE)]
+//! Variant1,
+//! }
+//!
+//! fn main() {
+//! let cli = Cli::parse();
+//! }
+//! ```
+//!
+//! Traits:
+//! - [`Parser`][crate::Parser] parses arguments into a `struct` (arguments) or `enum` (subcommands).
+//! - [`Args`][crate::Args] allows defining a set of re-usable arguments that get merged into their parent container.
+//! - [`Subcommand`][crate::Subcommand] defines available subcommands.
+//! - Subcommand arguments can be defined in a struct-variant or automatically flattened with a tuple-variant.
+//! - [`ValueEnum`][crate::ValueEnum] allows parsing a value directly into an `enum`, erroring on unsupported values.
+//! - The derive doesn't work on enums that contain non-unit variants, unless they are skipped
+//!
+//! *See also the [derive tutorial][crate::_derive::_tutorial] and [cookbook][crate::_cookbook]*
+//!
+//! ## Attributes
+//!
+//! ### Terminology
+//!
+//! **Raw attributes** are forwarded directly to the underlying [`clap` builder][crate::builder]. Any
+//! [`Command`][crate::Command], [`Arg`][crate::Arg], or [`PossibleValue`][crate::PossibleValue] method can be used as an attribute.
+//!
+//! Raw attributes come in two different syntaxes:
+//! ```rust,ignore
+//! #[clap(
+//! global = true, // name = arg form, neat for one-arg methods
+//! required_if_eq("out", "file") // name(arg1, arg2, ...) form.
+//! )]
+//! ```
+//!
+//! - `method = arg` can only be used for methods which take only one argument.
+//! - `method(arg1, arg2)` can be used with any method.
+//!
+//! As long as `method_name` is not one of the magical methods it will be
+//! translated into a mere method call.
+//!
+//! **Magic attributes** have post-processing done to them, whether that is
+//! - Providing of defaults
+//! - Special behavior is triggered off of it
+//!
+//! Magic attributes are more constrained in the syntax they support, usually just
+//! `<attr> = <value>` though some use `<attr>(<value>)` instead. See the specific
+//! magic attributes documentation for details. This allows users to access the
+//! raw behavior of an attribute via `<attr>(<value>)` syntax.
+//!
+//! **NOTE:** Some attributes are inferred from [Arg Types](#arg-types) and [Doc
+//! Comments](#doc-comments). Explicit attributes take precedence over inferred
+//! attributes.
+//!
+//! ### Command Attributes
+//!
+//! These correspond to a [`Command`][crate::Command] which is used for both top-level parsers and
+//! when defining subcommands.
+//!
+//! **Raw attributes:** Any [`Command` method][crate::Command] can also be used as an attribute,
+//! see [Terminology](#terminology) for syntax.
+//! - e.g. `#[clap(arg_required_else_help(true))]` would translate to `cmd.arg_required_else_help(true)`
+//!
+//! **Magic attributes:**
+//! - `name = <expr>`: [`Command::name`][crate::App::name]
+//! - When not present: [crate `name`](https://doc.rust-lang.org/cargo/reference/manifest.html#the-name-field) (if on [`Parser`][crate::Parser] container), variant name (if on [`Subcommand`][crate::Subcommand] variant)
+//! - `version [= <expr>]`: [`Command::version`][crate::App::version]
+//! - When not present: no version set
+//! - Without `<expr>`: defaults to [crate `version`](https://doc.rust-lang.org/cargo/reference/manifest.html#the-version-field)
+//! - `author [= <expr>]`: [`Command::author`][crate::App::author]
+//! - When not present: no author set
+//! - Without `<expr>`: defaults to [crate `authors`](https://doc.rust-lang.org/cargo/reference/manifest.html#the-authors-field)
+//! - `about [= <expr>]`: [`Command::about`][crate::App::about]
+//! - When not present: [Doc comment summary](#doc-comments)
+//! - Without `<expr>`: [crate `description`](https://doc.rust-lang.org/cargo/reference/manifest.html#the-description-field) ([`Parser`][crate::Parser] container)
+//! - **TIP:** When a doc comment is also present, you most likely want to add
+//! `#[clap(long_about = None)]` to clear the doc comment so only [`about`][crate::App::about]
+//! gets shown with both `-h` and `--help`.
+//! - `long_about = <expr>`: [`Command::long_about`][crate::App::long_about]
+//! - When not present: [Doc comment](#doc-comments) if there is a blank line, else nothing
+//! - `verbatim_doc_comment`: Minimizes pre-processing when converting doc comments to [`about`][crate::App::about] / [`long_about`][crate::App::long_about]
+//! - `next_display_order`: [`Command::next_display_order`][crate::App::next_display_order]
+//! - `next_help_heading`: [`Command::next_help_heading`][crate::App::next_help_heading]
+//! - When `flatten`ing [`Args`][crate::Args], this is scoped to just the args in this struct and any struct `flatten`ed into it
+//! - `rename_all = <string_literal>`: Override default field / variant name case conversion for [`Command::name`][crate::Command::name] / [`Arg::id`][crate::Arg::id]
+//! - When not present: `"kebab-case"`
+//! - Available values: `"camelCase"`, `"kebab-case"`, `"PascalCase"`, `"SCREAMING_SNAKE_CASE"`, `"snake_case"`, `"lower"`, `"UPPER"`, `"verbatim"`
+//! - `rename_all_env = <string_literal>`: Override default field name case conversion for env variables for [`Arg::env`][crate::Arg::env]
+//! - When not present: `"SCREAMING_SNAKE_CASE"`
+//! - Available values: `"camelCase"`, `"kebab-case"`, `"PascalCase"`, `"SCREAMING_SNAKE_CASE"`, `"snake_case"`, `"lower"`, `"UPPER"`, `"verbatim"`
+//!
+//! And for [`Subcommand`][crate::Subcommand] variants:
+//! - `skip`: Ignore this variant
+//! - `flatten`: Delegates to the variant for more subcommands (must implement
+//! [`Subcommand`][crate::Subcommand])
+//! - `subcommand`: Nest subcommands under the current set of subcommands (must implement
+//! [`Subcommand`][crate::Subcommand])
+//! - `external_subcommand`: [`Command::allow_external_subcommand(true)`][crate::App::allow_external_subcommands]
+//! - Variant must be either `Variant(Vec<String>)` or `Variant(Vec<OsString>)`
+//!
+//! ### Arg Attributes
+//!
+//! These correspond to a [`Arg`][crate::Arg].
+//!
+//! **Raw attributes:** Any [`Arg` method][crate::Arg] can also be used as an attribute, see [Terminology](#terminology) for syntax.
+//! - e.g. `#[clap(max_values(3))]` would translate to `arg.max_values(3)`
+//!
+//! **Magic attributes**:
+//! - `id = <expr>`: [`Arg::id`][crate::Arg::id]
+//! - When not present: case-converted field name is used
+//! - `name = <expr>`: [`Arg::id`][crate::Arg::id]
+//! - **Deprecated:** use `id`
+//! - `value_parser [= <expr>]`: [`Arg::value_parser`][crate::Arg::value_parser]
+//! - When not present: will auto-select an implementation based on the field type using
+//! [`value_parser!][crate::value_parser!]
+//! - When present but defaulted: opt-in to clap v4 semantics
+//! - Env parsing is now dependent on inferred parser
+//! - `PathBuf` will implicitly skip UTF-8 validation (before it required specifying
+//! `try_from_os_str`)
+//! - When present, implies `#[clap(action)]`
+//! - To register a custom type's [`ValueParser`][crate::builder::ValueParser], implement [`ValueParserFactory`][crate::builder::ValueParserFactory]
+//! - `action [= <expr>]`: [`Arg::action`][crate::Arg::action]
+//! - When not present: will auto-select an action based on the field type
+//! - When present but defaulted: opt-in to clap v4 semantics
+//! - When present, implies `#[clap(value_parser)]`
+//! - `args_override_self` is forced on for single flags
+//! - `help = <expr>`: [`Arg::help`][crate::Arg::help]
+//! - When not present: [Doc comment summary](#doc-comments)
+//! - `long_help = <expr>`: [`Arg::long_help`][crate::Arg::long_help]
+//! - When not present: [Doc comment](#doc-comments) if there is a blank line, else nothing
+//! - `verbatim_doc_comment`: Minimizes pre-processing when converting doc comments to [`help`][crate::Arg::help] / [`long_help`][crate::Arg::long_help]
+//! - `short [= <char>]`: [`Arg::short`][crate::Arg::short]
+//! - When not present: no short set
+//! - Without `<char>`: defaults to first character in the case-converted field name
+//! - `long [= <str>]`: [`Arg::long`][crate::Arg::long]
+//! - When not present: no long set
+//! - Without `<str>`: defaults to the case-converted field name
+//! - `env [= <str>]`: [`Arg::env`][crate::Arg::env] (needs [`env` feature][crate::_features] enabled)
+//! - When not present: no env set
+//! - Without `<str>`: defaults to the case-converted field name
+//! - `flatten`: Delegates to the field for more arguments (must implement [`Args`][crate::Args])
+//! - Only [`next_help_heading`][crate::Command::next_help_heading] can be used with `flatten`. See
+//! [clap-rs/clap#3269](https://github.com/clap-rs/clap/issues/3269) for why
+//! arg attributes are not generally supported.
+//! - **Tip:** Though we do apply a flattened [`Args`][crate::Args]'s Parent Command Attributes, this
+//! makes reuse harder. Generally prefer putting the cmd attributes on the
+//! [`Parser`][crate::Parser] or on the flattened field.
+//! - `subcommand`: Delegates definition of subcommands to the field (must implement
+//! [`Subcommand`][crate::Subcommand])
+//! - When `Option<T>`, the subcommand becomes optional
+//! - `from_global`: Read a [`Arg::global`][crate::Arg::global] argument (raw attribute), regardless of what subcommand you are in
+//! - `parse(<kind> [= <function>])`: [`Arg::validator`][crate::Arg::validator] and [`ArgMatches::values_of_t`][crate::ArgMatches::values_of_t]
+//! - **Deprecated:**
+//! - Use `value_parser(...)` for `from_str`, `try_from_str`, `from_os_str`, and `try_from_os_str`
+//! - Use `action(ArgAction::Count` for `from_occurrences`
+//! - Use `action(ArgAction::SetTrue` for `from_flag`
+//! - Default: `try_from_str`
+//! - Warning: for `Path` / `OsString`, be sure to use `try_from_os_str`
+//! - See [Arg Types](#arg-types) for more details
+//! - `value_enum`: Parse the value using the [`ValueEnum`][crate::ValueEnum]
+//! - `skip [= <expr>]`: Ignore this field, filling in with `<expr>`
+//! - Without `<expr>`: fills the field with `Default::default()`
+//! - `default_value = <str>`: [`Arg::default_value`][crate::Arg::default_value] and [`Arg::required(false)`][crate::Arg::required]
+//! - `default_value_t [= <expr>]`: [`Arg::default_value`][crate::Arg::default_value] and [`Arg::required(false)`][crate::Arg::required]
+//! - Requires `std::fmt::Display` or `#[clap(value_enum)]`
+//! - Without `<expr>`, relies on `Default::default()`
+//! - `default_values_t = <expr>`: [`Arg::default_values`][crate::Arg::default_values] and [`Arg::required(false)`][crate::Arg::required]
+//! - Requires field arg to be of type `Vec<T>` and `T` to implement `std::fmt::Display` or `#[clap(value_enum)]`
+//! - `<expr>` must implement `IntoIterator<T>`
+//! - `default_value_os_t [= <expr>]`: [`Arg::default_value_os`][crate::Arg::default_value_os] and [`Arg::required(false)`][crate::Arg::required]
+//! - Requires `std::convert::Into<OsString>` or `#[clap(value_enum)]`
+//! - Without `<expr>`, relies on `Default::default()`
+//! - `default_values_os_t = <expr>`: [`Arg::default_values_os`][crate::Arg::default_values_os] and [`Arg::required(false)`][crate::Arg::required]
+//! - Requires field arg to be of type `Vec<T>` and `T` to implement `std::convert::Into<OsString>` or `#[clap(value_enum)]`
+//! - `<expr>` must implement `IntoIterator<T>`
+//!
+//! ### ValueEnum Attributes
+//!
+//! - `rename_all = <string_literal>`: Override default field / variant name case conversion for [`PossibleValue::new`][crate::PossibleValue]
+//! - When not present: `"kebab-case"`
+//! - Available values: `"camelCase"`, `"kebab-case"`, `"PascalCase"`, `"SCREAMING_SNAKE_CASE"`, `"snake_case"`, `"lower"`, `"UPPER"`, `"verbatim"`
+//!
+//! ### Possible Value Attributes
+//!
+//! These correspond to a [`PossibleValue`][crate::PossibleValue].
+//!
+//! **Raw attributes:** Any [`PossibleValue` method][crate::PossibleValue] can also be used as an attribute, see [Terminology](#terminology) for syntax.
+//! - e.g. `#[clap(alias("foo"))]` would translate to `pv.alias("foo")`
+//!
+//! **Magic attributes**:
+//! - `name = <expr>`: [`PossibleValue::new`][crate::PossibleValue::new]
+//! - When not present: case-converted field name is used
+//! - `help = <expr>`: [`PossibleValue::help`][crate::PossibleValue::help]
+//! - When not present: [Doc comment summary](#doc-comments)
+//!
+//! ## Arg Types
+//!
+//! `clap` assumes some intent based on the type used:
+//!
+//! | Type | Effect | Implies |
+//! |---------------------|--------------------------------------|------------------------------------------------------------------|
+//! | `bool` | flag | `#[clap(parse(from_flag))]` |
+//! | `Option<T>` | optional argument | `.takes_value(true).required(false)` |
+//! | `Option<Option<T>>` | optional value for optional argument | `.takes_value(true).required(false).min_values(0).max_values(1)` |
+//! | `T` | required argument | `.takes_value(true).required(!has_default)` |
+//! | `Vec<T>` | `0..` occurrences of argument | `.takes_value(true).required(false).multiple_occurrences(true)` |
+//! | `Option<Vec<T>>` | `0..` occurrences of argument | `.takes_value(true).required(false).multiple_occurrences(true)` |
+//!
+//! Notes:
+//! - For custom type behavior, you can override the implied attributes/settings and/or set additional ones
+//! - For example, see [custom-bool](./custom-bool.md)
+//! - `Option<Vec<T>>` will be `None` instead of `vec![]` if no arguments are provided.
+//! - This gives the user some flexibility in designing their argument, like with `min_values(0)`
+//!
+//! You can then support your custom type with `#[clap(parse(<kind> [= <function>]))]`:
+//!
+//! | `<kind>` | Signature | Default `<function>` |
+//! |--------------------------|---------------------------------------|---------------------------------|
+//! | `from_str` | `fn(&str) -> T` | `::std::convert::From::from` |
+//! | `try_from_str` (default) | `fn(&str) -> Result<T, E>` | `::std::str::FromStr::from_str` |
+//! | `from_os_str` | `fn(&OsStr) -> T` | `::std::convert::From::from` |
+//! | `try_from_os_str` | `fn(&OsStr) -> Result<T, E>` | (no default function) |
+//! | `from_occurrences` | `fn(u64) -> T` | `value as T` |
+//! | `from_flag` | `fn(bool) -> T` | `::std::convert::From::from` |
+//!
+//! Notes:
+//! - `from_os_str`:
+//! - Implies `arg.takes_value(true).allow_invalid_utf8(true)`
+//! - `try_from_os_str`:
+//! - Implies `arg.takes_value(true).allow_invalid_utf8(true)`
+//! - `from_occurrences`:
+//! - Implies `arg.takes_value(false).multiple_occurrences(true)`
+//! - Reads from `clap::ArgMatches::occurrences_of` rather than a `get_one` function
+//! - Note: operations on values, like `default_value`, are unlikely to do what you want
+//! - `from_flag`
+//! - Implies `arg.takes_value(false)`
+//! - Reads from `clap::ArgMatches::is_present` rather than a `get_one` function
+//! - Note: operations on values, like `default_value`, are unlikely to do what you want
+//!
+//! **Warning:**
+//! - To support non-UTF8 paths, you should use `#[clap(value_parser)]` otherwise
+//! `clap` will parse it as a `String` which will fail on some paths.
+//!
+//! ## Doc Comments
+//!
+//! In clap, help messages for the whole binary can be specified
+//! via [`Command::about`][crate::App::about] and [`Command::long_about`][crate::App::long_about] while help messages
+//! for individual arguments can be specified via [`Arg::help`][crate::Arg::help] and [`Arg::long_help`][crate::Arg::long_help].
+//!
+//! `long_*` variants are used when user calls the program with
+//! `--help` and "short" variants are used with `-h` flag.
+//!
+//! ```rust
+//! # use clap::Parser;
+//!
+//! #[derive(Parser)]
+//! #[clap(about = "I am a program and I work, just pass `-h`", long_about = None)]
+//! struct Foo {
+//! #[clap(short, help = "Pass `-h` and you'll see me!")]
+//! bar: String,
+//! }
+//! ```
+//!
+//! For convenience, doc comments can be used instead of raw methods
+//! (this example works exactly like the one above):
+//!
+//! ```rust
+//! # use clap::Parser;
+//!
+//! #[derive(Parser)]
+//! /// I am a program and I work, just pass `-h`
+//! struct Foo {
+//! /// Pass `-h` and you'll see me!
+//! bar: String,
+//! }
+//! ```
+//!
+//! **NOTE:** Attributes have priority over doc comments!
+//!
+//! **Top level doc comments always generate `Command::about/long_about` calls!**
+//! If you really want to use the `Command::about/long_about` methods (you likely don't),
+//! use the `about` / `long_about` attributes to override the calls generated from
+//! the doc comment. To clear `long_about`, you can use
+//! `#[clap(long_about = None)]`.
+//!
+//! **TIP:** Set `#![deny(missing_docs)]` to catch missing `--help` documentation at compile time.
+//!
+//! ### Pre-processing
+//!
+//! ```rust
+//! # use clap::Parser;
+//! #[derive(Parser)]
+//! /// Hi there, I'm Robo!
+//! ///
+//! /// I like beeping, stumbling, eating your electricity,
+//! /// and making records of you singing in a shower.
+//! /// Pay up, or I'll upload it to youtube!
+//! struct Robo {
+//! /// Call my brother SkyNet.
+//! ///
+//! /// I am artificial superintelligence. I won't rest
+//! /// until I'll have destroyed humanity. Enjoy your
+//! /// pathetic existence, you mere mortals.
+//! #[clap(long, action)]
+//! kill_all_humans: bool,
+//! }
+//! ```
+//!
+//! A doc comment consists of three parts:
+//! - Short summary
+//! - A blank line (whitespace only)
+//! - Detailed description, all the rest
+//!
+//! The summary corresponds with `Command::about` / `Arg::help`. When a blank line is
+//! present, the whole doc comment will be passed to `Command::long_about` /
+//! `Arg::long_help`. Or in other words, a doc may result in just a `Command::about` /
+//! `Arg::help` or `Command::about` / `Arg::help` and `Command::long_about` /
+//! `Arg::long_help`
+//!
+//! In addition, when `verbatim_doc_comment` is not present, `clap` applies some preprocessing, including:
+//!
+//! - Strip leading and trailing whitespace from every line, if present.
+//!
+//! - Strip leading and trailing blank lines, if present.
+//!
+//! - Interpret each group of non-empty lines as a word-wrapped paragraph.
+//!
+//! We replace newlines within paragraphs with spaces to allow the output
+//! to be re-wrapped to the terminal width.
+//!
+//! - Strip any excess blank lines so that there is exactly one per paragraph break.
+//!
+//! - If the first paragraph ends in exactly one period,
+//! remove the trailing period (i.e. strip trailing periods but not trailing ellipses).
+//!
+//! Sometimes you don't want this preprocessing to apply, for example the comment contains
+//! some ASCII art or markdown tables, you would need to preserve LFs along with
+//! blank lines and the leading/trailing whitespace. When you pass use the
+//! `verbatim_doc_comment` magic attribute, you preserve
+//! them.
+//!
+//! **Note:** Keep in mind that `verbatim_doc_comment` will *still*
+//! - Remove one leading space from each line, even if this attribute is present,
+//! to allow for a space between `///` and the content.
+//! - Remove leading and trailing blank lines
+//!
+//! ## Mixing Builder and Derive APIs
+//!
+//! The builder and derive APIs do not live in isolation. They can work together, which is
+//! especially helpful if some arguments can be specified at compile-time while others must be
+//! specified at runtime.
+//!
+//! ### Using derived arguments in a builder application
+//!
+//! When using the derive API, you can `#[clap(flatten)]` a struct deriving `Args` into a struct
+//! deriving `Args` or `Parser`. This example shows how you can augment a `Command` instance
+//! created using the builder API with `Args` created using the derive API.
+//!
+//! It uses the [`Args::augment_args`][crate::Args::augment_args] method to add the arguments to
+//! the `Command` instance.
+//!
+//! Crates such as [clap-verbosity-flag](https://github.com/rust-cli/clap-verbosity-flag) provide
+//! structs that implement `Args`. Without the technique shown in this example, it would not be
+//! possible to use such crates with the builder API.
+//!
+//! For example:
+//! ```rust
+#![doc = include_str!("../../examples/derive_ref/augment_args.rs")]
+//! ```
+//!
+//! ### Using derived subcommands in a builder application
+//!
+//! When using the derive API, you can use `#[clap(subcommand)]` inside the struct to add
+//! subcommands. The type of the field is usually an enum that derived `Parser`. However, you can
+//! also add the subcommands in that enum to a `Command` instance created with the builder API.
+//!
+//! It uses the [`Subcommand::augment_subcommands`][crate::Subcommand::augment_subcommands] method
+//! to add the subcommands to the `Command` instance.
+//!
+//! For example:
+//! ```rust
+#![doc = include_str!("../../examples/derive_ref/augment_subcommands.rs")]
+//! ```
+//!
+//! ### Adding hand-implemented subcommands to a derived application
+//!
+//! When using the derive API, you can use `#[clap(subcommand)]` inside the struct to add
+//! subcommands. The type of the field is usually an enum that derived `Parser`. However, you can
+//! also implement the `Subcommand` trait manually on this enum (or any other type) and it can
+//! still be used inside the struct created with the derive API. The implementation of the
+//! `Subcommand` trait will use the builder API to add the subcommands to the `Command` instance
+//! created behind the scenes for you by the derive API.
+//!
+//! Notice how in the previous example we used
+//! [`augment_subcommands`][crate::Subcommand::augment_subcommands] on an enum that derived
+//! `Parser`, whereas now we implement
+//! [`augment_subcommands`][crate::Subcommand::augment_subcommands] ourselves, but the derive API
+//! calls it automatically since we used the `#[clap(subcommand)]` attribute.
+//!
+//! For example:
+//! ```rust
+#![doc = include_str!("../../examples/derive_ref/hand_subcommand.rs")]
+//! ```
+//!
+//! ### Flattening hand-implemented args into a derived application
+//!
+//! When using the derive API, you can use `#[clap(flatten)]` inside the struct to add arguments as
+//! if they were added directly to the containing struct. The type of the field is usually an
+//! struct that derived `Args`. However, you can also implement the `Args` trait manually on this
+//! struct (or any other type) and it can still be used inside the struct created with the derive
+//! API. The implementation of the `Args` trait will use the builder API to add the arguments to
+//! the `Command` instance created behind the scenes for you by the derive API.
+//!
+//! Notice how in the previous example we used [`augment_args`][crate::Args::augment_args] on the
+//! struct that derived `Parser`, whereas now we implement
+//! [`augment_args`][crate::Args::augment_args] ourselves, but the derive API calls it
+//! automatically since we used the `#[clap(flatten)]` attribute.
+//!
+//! For example:
+//! ```rust
+#![doc = include_str!("../../examples/derive_ref/flatten_hand_args.rs")]
+//! ```
+//!
+//! ## Tips
+//!
+//! - To get access to a [`Command`][crate::Command] call
+//! [`CommandFactory::command`][crate::CommandFactory::command] (implemented when deriving
+//! [`Parser`][crate::Parser])
+//! - Proactively check for bad [`Command`][crate::Command] configurations by calling
+//! [`Command::debug_assert`][crate::App::debug_assert] in a test
+//! ([example](../tutorial_derive/05_01_assert.rs))
+
+pub mod _tutorial;
+#[doc(inline)]
+pub use crate::_cookbook;