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feat(derive): Allow destructively constructing from ArgMatches
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@epage
epage committed May 18, 2022
1 parent b202eed commit 1446be8
Showing 1 changed file with 66 additions and 18 deletions.
84 changes: 66 additions & 18 deletions src/derive.rs
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Expand Up @@ -79,9 +79,9 @@ use std::ffi::OsString;
pub trait Parser: FromArgMatches + CommandFactory + Sized {
/// Parse from `std::env::args_os()`, exit on error
fn parse() -> Self {
let matches = <Self as CommandFactory>::command().get_matches();
let res =
<Self as FromArgMatches>::from_arg_matches(&matches).map_err(format_error::<Self>);
let mut matches = <Self as CommandFactory>::command().get_matches();
let res = <Self as FromArgMatches>::from_arg_matches_mut(&mut matches)
.map_err(format_error::<Self>);
match res {
Ok(s) => s,
Err(e) => {
Expand All @@ -94,8 +94,8 @@ pub trait Parser: FromArgMatches + CommandFactory + Sized {

/// Parse from `std::env::args_os()`, return Err on error.
fn try_parse() -> Result<Self, Error> {
let matches = <Self as CommandFactory>::command().try_get_matches()?;
<Self as FromArgMatches>::from_arg_matches(&matches).map_err(format_error::<Self>)
let mut matches = <Self as CommandFactory>::command().try_get_matches()?;
<Self as FromArgMatches>::from_arg_matches_mut(&mut matches).map_err(format_error::<Self>)
}

/// Parse from iterator, exit on error
Expand All @@ -104,9 +104,9 @@ pub trait Parser: FromArgMatches + CommandFactory + Sized {
I: IntoIterator<Item = T>,
T: Into<OsString> + Clone,
{
let matches = <Self as CommandFactory>::command().get_matches_from(itr);
let res =
<Self as FromArgMatches>::from_arg_matches(&matches).map_err(format_error::<Self>);
let mut matches = <Self as CommandFactory>::command().get_matches_from(itr);
let res = <Self as FromArgMatches>::from_arg_matches_mut(&mut matches)
.map_err(format_error::<Self>);
match res {
Ok(s) => s,
Err(e) => {
Expand All @@ -123,8 +123,8 @@ pub trait Parser: FromArgMatches + CommandFactory + Sized {
I: IntoIterator<Item = T>,
T: Into<OsString> + Clone,
{
let matches = <Self as CommandFactory>::command().try_get_matches_from(itr)?;
<Self as FromArgMatches>::from_arg_matches(&matches).map_err(format_error::<Self>)
let mut matches = <Self as CommandFactory>::command().try_get_matches_from(itr)?;
<Self as FromArgMatches>::from_arg_matches_mut(&mut matches).map_err(format_error::<Self>)
}

/// Update from iterator, exit on error
Expand All @@ -133,8 +133,8 @@ pub trait Parser: FromArgMatches + CommandFactory + Sized {
I: IntoIterator<Item = T>,
T: Into<OsString> + Clone,
{
let matches = <Self as CommandFactory>::command_for_update().get_matches_from(itr);
let res = <Self as FromArgMatches>::update_from_arg_matches(self, &matches)
let mut matches = <Self as CommandFactory>::command_for_update().get_matches_from(itr);
let res = <Self as FromArgMatches>::update_from_arg_matches_mut(self, &mut matches)
.map_err(format_error::<Self>);
if let Err(e) = res {
// Since this is more of a development-time error, we aren't doing as fancy of a quit
Expand All @@ -149,8 +149,9 @@ pub trait Parser: FromArgMatches + CommandFactory + Sized {
I: IntoIterator<Item = T>,
T: Into<OsString> + Clone,
{
let matches = <Self as CommandFactory>::command_for_update().try_get_matches_from(itr)?;
<Self as FromArgMatches>::update_from_arg_matches(self, &matches)
let mut matches =
<Self as CommandFactory>::command_for_update().try_get_matches_from(itr)?;
<Self as FromArgMatches>::update_from_arg_matches_mut(self, &mut matches)
.map_err(format_error::<Self>)
}

Expand All @@ -165,11 +166,11 @@ pub trait Parser: FromArgMatches + CommandFactory + Sized {
<Self as CommandFactory>::command()
}

/// Deprecated, `StructOpt::from_clap` replaced with [`FromArgMatches::from_arg_matches`] (derive as part of
/// Deprecated, `StructOpt::from_clap` replaced with [`FromArgMatches::from_arg_matches_mut`] (derive as part of
/// [`Parser`])
#[deprecated(
since = "3.0.0",
note = "`StructOpt::from_clap` is replaced with `FromArgMatches::from_arg_matches` (derived as part of `Parser`)"
note = "`StructOpt::from_clap` is replaced with `FromArgMatches::from_arg_matches_mut` (derived as part of `Parser`)"
)]
#[doc(hidden)]
fn from_clap(matches: &ArgMatches) -> Self {
Expand Down Expand Up @@ -232,7 +233,7 @@ pub trait Parser: FromArgMatches + CommandFactory + Sized {
pub trait CommandFactory: Sized {
/// Build a [`Command`] that can instantiate `Self`.
///
/// See [`FromArgMatches::from_arg_matches`] for instantiating `Self`.
/// See [`FromArgMatches::from_arg_matches_mut`] for instantiating `Self`.
fn command<'help>() -> Command<'help> {
#[allow(deprecated)]
Self::into_app()
Expand All @@ -242,7 +243,7 @@ pub trait CommandFactory: Sized {
fn into_app<'help>() -> Command<'help>;
/// Build a [`Command`] that can update `self`.
///
/// See [`FromArgMatches::update_from_arg_matches`] for updating `self`.
/// See [`FromArgMatches::update_from_arg_matches_mut`] for updating `self`.
fn command_for_update<'help>() -> Command<'help> {
#[allow(deprecated)]
Self::into_app_for_update()
Expand Down Expand Up @@ -293,8 +294,49 @@ pub trait FromArgMatches: Sized {
/// ```
fn from_arg_matches(matches: &ArgMatches) -> Result<Self, Error>;

/// Instantiate `Self` from [`ArgMatches`], parsing the arguments as needed.
///
/// Motivation: If our application had two CLI options, `--name
/// <STRING>` and the flag `--debug`, we may create a struct as follows:
///
#[cfg_attr(not(feature = "derive"), doc = " ```ignore")]
#[cfg_attr(feature = "derive", doc = " ```no_run")]
/// struct Context {
/// name: String,
/// debug: bool
/// }
/// ```
///
/// We then need to convert the `ArgMatches` that `clap` generated into our struct.
/// `from_arg_matches_mut` serves as the equivalent of:
///
#[cfg_attr(not(feature = "derive"), doc = " ```ignore")]
#[cfg_attr(feature = "derive", doc = " ```no_run")]
/// # use clap::ArgMatches;
/// # struct Context {
/// # name: String,
/// # debug: bool
/// # }
/// impl From<ArgMatches> for Context {
/// fn from(m: ArgMatches) -> Self {
/// Context {
/// name: m.value_of("name").unwrap().to_string(),
/// debug: m.is_present("debug"),
/// }
/// }
/// }
/// ```
fn from_arg_matches_mut(matches: &mut ArgMatches) -> Result<Self, Error> {
Self::from_arg_matches(matches)
}

/// Assign values from `ArgMatches` to `self`.
fn update_from_arg_matches(&mut self, matches: &ArgMatches) -> Result<(), Error>;

/// Assign values from `ArgMatches` to `self`.
fn update_from_arg_matches_mut(&mut self, matches: &mut ArgMatches) -> Result<(), Error> {
self.update_from_arg_matches(matches)
}
}

/// Parse a set of arguments into a user-defined container.
Expand Down Expand Up @@ -480,9 +522,15 @@ impl<T: FromArgMatches> FromArgMatches for Box<T> {
fn from_arg_matches(matches: &ArgMatches) -> Result<Self, Error> {
<T as FromArgMatches>::from_arg_matches(matches).map(Box::new)
}
fn from_arg_matches_mut(matches: &mut ArgMatches) -> Result<Self, Error> {
<T as FromArgMatches>::from_arg_matches_mut(matches).map(Box::new)
}
fn update_from_arg_matches(&mut self, matches: &ArgMatches) -> Result<(), Error> {
<T as FromArgMatches>::update_from_arg_matches(self, matches)
}
fn update_from_arg_matches_mut(&mut self, matches: &mut ArgMatches) -> Result<(), Error> {
<T as FromArgMatches>::update_from_arg_matches_mut(self, matches)
}
}

impl<T: Args> Args for Box<T> {
Expand Down

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