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Opt

noargs

Enum Opt 

Source 
pub enum Opt {
    Long {
        spec: OptSpec,
        metadata: Metadata,
        index: usize,
        value: String,
    },
    Short {
        spec: OptSpec,
        metadata: Metadata,
        index: usize,
        value: String,
    },
    Env {
        spec: OptSpec,
        metadata: Metadata,
        value: String,
    },
    Default {
        spec: OptSpec,
        metadata: Metadata,
    },
    Example {
        spec: OptSpec,
        metadata: Metadata,
    },
    MissingValue {
        spec: OptSpec,
        long: bool,
    },
    None {
        spec: OptSpec,
    },
}
Expand description

A named argument with value.

Variants§

§

Long

Fields

§spec: OptSpec
§metadata: Metadata
§index: usize
§value: String
§

Short

Fields

§spec: OptSpec
§metadata: Metadata
§index: usize
§value: String
§

Env

Fields

§spec: OptSpec
§metadata: Metadata
§value: String
§

Default

Fields

§spec: OptSpec
§metadata: Metadata
§

Example

Fields

§spec: OptSpec
§metadata: Metadata
§

MissingValue

Fields

§spec: OptSpec
§long: bool
§

None

Fields

§spec: OptSpec

Implementations§

Source§

impl Opt

Source

pub fn spec(&self) -> OptSpec

Returns the specification of this option.

Source

pub fn is_present(&self) -> bool

Returns true if this option is present.

Source

pub fn is_value_present(&self) -> bool

Returns true if this option is present and has a value.

Source

pub fn present(self) -> Option<Self>

Returns Some(self) if this option is present.

Source

pub fn then<F, T, E>(self, f: F) -> Result<T, Error>
where F: FnOnce(Self) -> Result<T, E>, E: Display,

Applies additional conversion or validation to the option.

This method allows for chaining transformations and validations when an option is present. It first checks if the option has a value and then applies the provided function.

§Examples
let mut args = noargs::RawArgs::new(["example", "--num=42"].iter().map(|a| a.to_string()));
let opt = noargs::opt("num").take(&mut args);

// Parse as number and ensure it's positive
let num = opt.then(|opt| -> Result<_, Box<dyn std::error::Error>> {
    let n: i32 = opt.value().parse()?;
    if n <= 0 {
        return Err("number must be positive".into());
    }
    Ok(n)
})?;
§Errors
Examples found in repository?
examples/subcommands.rs (line 70)
55fn try_run_sum(args: &mut noargs::RawArgs) -> noargs::Result<bool> {
56    if !noargs::cmd("sum")
57        .doc("Add two integers")
58        .take(args)
59        .is_present()
60    {
61        return Ok(false);
62    }
63
64    let repeat: usize = noargs::opt("repeat")
65        .short('r')
66        .ty("N")
67        .doc("Print result multiple times")
68        .default("1")
69        .take(args)
70        .then(|o| o.value().parse())?;
71    let left: i64 = noargs::arg("<LEFT>")
72        .doc("Left operand")
73        .example("3")
74        .take(args)
75        .then(|a| a.value().parse())?;
76    let right: i64 = noargs::arg("<RIGHT>")
77        .doc("Right operand")
78        .example("4")
79        .take(args)
80        .then(|a| a.value().parse())?;
81
82    if args.metadata().help_mode {
83        return Ok(true);
84    }
85
86    let total = left + right;
87    for _ in 0..repeat {
88        println!("{total}");
89    }
90    Ok(true)
91}
More examples
Hide additional examples
examples/arrays.rs (line 43)
1fn main() -> noargs::Result<()> {
2    let mut args = noargs::raw_args();
3    args.metadata_mut().app_name = env!("CARGO_PKG_NAME");
4    args.metadata_mut().app_description = env!("CARGO_PKG_DESCRIPTION");
5
6    if noargs::VERSION_FLAG.take(&mut args).is_present() {
7        println!("{} {}", env!("CARGO_PKG_NAME"), env!("CARGO_PKG_VERSION"));
8        return Ok(());
9    }
10    noargs::HELP_FLAG.take_help(&mut args);
11
12    // Same-name options can be collected by calling take() in a loop.
13    let include_opt = noargs::opt("include")
14        .short('I')
15        .ty("PATH")
16        .doc("Include path (can be specified multiple times)");
17    let mut includes = Vec::<String>::new();
18    while let Some(path) = include_opt
19        .take(&mut args)
20        .present_and_then(|o| o.value().parse())?
21    {
22        includes.push(path);
23    }
24
25    let label_opt = noargs::opt("label")
26        .short('l')
27        .ty("LABEL")
28        .doc("Label value (can be specified multiple times)");
29    let mut labels = Vec::<String>::new();
30    while let Some(label) = label_opt
31        .take(&mut args)
32        .present_and_then(|o| o.value().parse())?
33    {
34        labels.push(label);
35    }
36
37    let output: String = noargs::opt("output")
38        .short('o')
39        .ty("PATH")
40        .doc("Output path")
41        .default("summary.txt")
42        .take(&mut args)
43        .then(|o| o.value().parse())?;
44
45    // Positional arrays are handled with one required argument + optional rest.
46    // Naming convention: use `<NAME>...` for required-many and `[NAME]...` for optional-many.
47    // The `<>` / `[]` / `...` markers are cosmetic (used only in help output);
48    // required-ness is enforced below: `.then()` makes the first input required,
49    // the loop with `.present_and_then()` consumes zero or more rest inputs.
50    let first_input: String = noargs::arg("<INPUT>")
51        .doc("First input (required)")
52        .example("a.txt")
53        .take(&mut args)
54        .then(|a| a.value().parse())?;
55    let rest_input_arg = noargs::arg("[INPUT]...").doc("Additional inputs");
56    let mut inputs = vec![first_input];
57    while let Some(input) = rest_input_arg
58        .take(&mut args)
59        .present_and_then(|a| a.value().parse())?
60    {
61        inputs.push(input);
62    }
63
64    if let Some(help) = args.finish()? {
65        print!("{help}");
66        return Ok(());
67    }
68
69    println!("includes={includes:?}");
70    println!("labels={labels:?}");
71    println!("inputs={inputs:?}");
72    println!("output={output}");
73    Ok(())
74}
examples/basics.rs (line 34)
1fn main() -> noargs::Result<()> {
2    let mut args = noargs::raw_args();
3    args.metadata_mut().app_name = env!("CARGO_PKG_NAME");
4    args.metadata_mut().app_description = env!("CARGO_PKG_DESCRIPTION");
5
6    if noargs::VERSION_FLAG.take(&mut args).is_present() {
7        println!("{} {}", env!("CARGO_PKG_NAME"), env!("CARGO_PKG_VERSION"));
8        return Ok(());
9    }
10    noargs::HELP_FLAG.take_help(&mut args);
11
12    // Important: call flag()/opt() before arg().
13    // Otherwise values like "-v" — or any unknown "--bogus" — can be silently
14    // consumed as positional arguments.
15    //
16    // Required option / positional: set example("...") so help mode renders
17    // a meaningful Usage / Example line. Optional fields covered by default()
18    // or present_and_then() do not need example().
19    let verbose = noargs::flag("verbose")
20        .short('v')
21        .doc("Enable verbose output")
22        .take(&mut args)
23        .is_present();
24    let dry_run = noargs::flag("dry-run")
25        .doc("Print parsed values and exit without running processing")
26        .take(&mut args)
27        .is_present();
28    let retries: usize = noargs::opt("retries")
29        .short('r')
30        .ty("N")
31        .doc("How many times to retry")
32        .default("1")
33        .take(&mut args)
34        .then(|o| o.value().parse())?;
35    let endpoint: String = noargs::opt("endpoint")
36        .ty("URL")
37        .doc("Server endpoint")
38        .env("NOARGS_ENDPOINT")
39        .default("http://localhost:8080")
40        .take(&mut args)
41        .then(|o| o.value().parse())?;
42    let format: String = noargs::opt("format")
43        .ty("FORMAT")
44        .doc("Output format")
45        .example("json")
46        .take(&mut args)
47        .then(|o| o.value().parse())?;
48    let timeout_secs: Option<u64> = noargs::opt("timeout")
49        .ty("SECONDS")
50        .doc("Optional timeout in seconds")
51        .take(&mut args)
52        .present_and_then(|o| o.value().parse())?;
53
54    let input: String = noargs::arg("<INPUT>")
55        .doc("Input file path")
56        .example("input.txt")
57        .take(&mut args)
58        .then(|a| a.value().parse())?;
59    // Optional positional with default(): the value is always a String —
60    // absent uses "out.txt", present uses the given path.
61    // For "absent vs present" distinction, use present_and_then() and bind
62    // to Option<String> — see the README's [BAZ] example.
63    let output: String = noargs::arg("[OUTPUT]")
64        .doc("Output file path")
65        .default("out.txt")
66        .take(&mut args)
67        .then(|a| a.value().parse())?;
68
69    if let Some(help) = args.finish()? {
70        // When help is requested, finish() returns the built help text.
71        // Print it here and exit without running application logic.
72        print!("{help}");
73        return Ok(());
74    }
75
76    if dry_run {
77        println!(
78            "dry-run: verbose={verbose}, retries={retries}, endpoint={endpoint}, format={format}, timeout_secs={timeout_secs:?}, input={input}, output={output}"
79        );
80        return Ok(());
81    }
82
83    println!("processing: {input} -> {output}");
84    println!("using endpoint={endpoint}, format={format}, retries={retries}");
85    if verbose {
86        println!("verbose: timeout_secs={timeout_secs:?}");
87    }
88
89    Ok(())
90}
Source

pub fn present_and_then<F, T, E>(self, f: F) -> Result<Option<T>, Error>
where F: FnOnce(Self) -> Result<T, E>, E: Display,

Shorthand for self.present().map(|opt| opt.then(f)).transpose().

Examples found in repository?
examples/arrays.rs (line 20)
1fn main() -> noargs::Result<()> {
2    let mut args = noargs::raw_args();
3    args.metadata_mut().app_name = env!("CARGO_PKG_NAME");
4    args.metadata_mut().app_description = env!("CARGO_PKG_DESCRIPTION");
5
6    if noargs::VERSION_FLAG.take(&mut args).is_present() {
7        println!("{} {}", env!("CARGO_PKG_NAME"), env!("CARGO_PKG_VERSION"));
8        return Ok(());
9    }
10    noargs::HELP_FLAG.take_help(&mut args);
11
12    // Same-name options can be collected by calling take() in a loop.
13    let include_opt = noargs::opt("include")
14        .short('I')
15        .ty("PATH")
16        .doc("Include path (can be specified multiple times)");
17    let mut includes = Vec::<String>::new();
18    while let Some(path) = include_opt
19        .take(&mut args)
20        .present_and_then(|o| o.value().parse())?
21    {
22        includes.push(path);
23    }
24
25    let label_opt = noargs::opt("label")
26        .short('l')
27        .ty("LABEL")
28        .doc("Label value (can be specified multiple times)");
29    let mut labels = Vec::<String>::new();
30    while let Some(label) = label_opt
31        .take(&mut args)
32        .present_and_then(|o| o.value().parse())?
33    {
34        labels.push(label);
35    }
36
37    let output: String = noargs::opt("output")
38        .short('o')
39        .ty("PATH")
40        .doc("Output path")
41        .default("summary.txt")
42        .take(&mut args)
43        .then(|o| o.value().parse())?;
44
45    // Positional arrays are handled with one required argument + optional rest.
46    // Naming convention: use `<NAME>...` for required-many and `[NAME]...` for optional-many.
47    // The `<>` / `[]` / `...` markers are cosmetic (used only in help output);
48    // required-ness is enforced below: `.then()` makes the first input required,
49    // the loop with `.present_and_then()` consumes zero or more rest inputs.
50    let first_input: String = noargs::arg("<INPUT>")
51        .doc("First input (required)")
52        .example("a.txt")
53        .take(&mut args)
54        .then(|a| a.value().parse())?;
55    let rest_input_arg = noargs::arg("[INPUT]...").doc("Additional inputs");
56    let mut inputs = vec![first_input];
57    while let Some(input) = rest_input_arg
58        .take(&mut args)
59        .present_and_then(|a| a.value().parse())?
60    {
61        inputs.push(input);
62    }
63
64    if let Some(help) = args.finish()? {
65        print!("{help}");
66        return Ok(());
67    }
68
69    println!("includes={includes:?}");
70    println!("labels={labels:?}");
71    println!("inputs={inputs:?}");
72    println!("output={output}");
73    Ok(())
74}
More examples
Hide additional examples
examples/basics.rs (line 52)
1fn main() -> noargs::Result<()> {
2    let mut args = noargs::raw_args();
3    args.metadata_mut().app_name = env!("CARGO_PKG_NAME");
4    args.metadata_mut().app_description = env!("CARGO_PKG_DESCRIPTION");
5
6    if noargs::VERSION_FLAG.take(&mut args).is_present() {
7        println!("{} {}", env!("CARGO_PKG_NAME"), env!("CARGO_PKG_VERSION"));
8        return Ok(());
9    }
10    noargs::HELP_FLAG.take_help(&mut args);
11
12    // Important: call flag()/opt() before arg().
13    // Otherwise values like "-v" — or any unknown "--bogus" — can be silently
14    // consumed as positional arguments.
15    //
16    // Required option / positional: set example("...") so help mode renders
17    // a meaningful Usage / Example line. Optional fields covered by default()
18    // or present_and_then() do not need example().
19    let verbose = noargs::flag("verbose")
20        .short('v')
21        .doc("Enable verbose output")
22        .take(&mut args)
23        .is_present();
24    let dry_run = noargs::flag("dry-run")
25        .doc("Print parsed values and exit without running processing")
26        .take(&mut args)
27        .is_present();
28    let retries: usize = noargs::opt("retries")
29        .short('r')
30        .ty("N")
31        .doc("How many times to retry")
32        .default("1")
33        .take(&mut args)
34        .then(|o| o.value().parse())?;
35    let endpoint: String = noargs::opt("endpoint")
36        .ty("URL")
37        .doc("Server endpoint")
38        .env("NOARGS_ENDPOINT")
39        .default("http://localhost:8080")
40        .take(&mut args)
41        .then(|o| o.value().parse())?;
42    let format: String = noargs::opt("format")
43        .ty("FORMAT")
44        .doc("Output format")
45        .example("json")
46        .take(&mut args)
47        .then(|o| o.value().parse())?;
48    let timeout_secs: Option<u64> = noargs::opt("timeout")
49        .ty("SECONDS")
50        .doc("Optional timeout in seconds")
51        .take(&mut args)
52        .present_and_then(|o| o.value().parse())?;
53
54    let input: String = noargs::arg("<INPUT>")
55        .doc("Input file path")
56        .example("input.txt")
57        .take(&mut args)
58        .then(|a| a.value().parse())?;
59    // Optional positional with default(): the value is always a String —
60    // absent uses "out.txt", present uses the given path.
61    // For "absent vs present" distinction, use present_and_then() and bind
62    // to Option<String> — see the README's [BAZ] example.
63    let output: String = noargs::arg("[OUTPUT]")
64        .doc("Output file path")
65        .default("out.txt")
66        .take(&mut args)
67        .then(|a| a.value().parse())?;
68
69    if let Some(help) = args.finish()? {
70        // When help is requested, finish() returns the built help text.
71        // Print it here and exit without running application logic.
72        print!("{help}");
73        return Ok(());
74    }
75
76    if dry_run {
77        println!(
78            "dry-run: verbose={verbose}, retries={retries}, endpoint={endpoint}, format={format}, timeout_secs={timeout_secs:?}, input={input}, output={output}"
79        );
80        return Ok(());
81    }
82
83    println!("processing: {input} -> {output}");
84    println!("using endpoint={endpoint}, format={format}, retries={retries}");
85    if verbose {
86        println!("verbose: timeout_secs={timeout_secs:?}");
87    }
88
89    Ok(())
90}
Source

pub fn value(&self) -> &str

Returns the raw value of this option, or an empty string if not present.

Examples found in repository?
examples/subcommands.rs (line 70)
55fn try_run_sum(args: &mut noargs::RawArgs) -> noargs::Result<bool> {
56    if !noargs::cmd("sum")
57        .doc("Add two integers")
58        .take(args)
59        .is_present()
60    {
61        return Ok(false);
62    }
63
64    let repeat: usize = noargs::opt("repeat")
65        .short('r')
66        .ty("N")
67        .doc("Print result multiple times")
68        .default("1")
69        .take(args)
70        .then(|o| o.value().parse())?;
71    let left: i64 = noargs::arg("<LEFT>")
72        .doc("Left operand")
73        .example("3")
74        .take(args)
75        .then(|a| a.value().parse())?;
76    let right: i64 = noargs::arg("<RIGHT>")
77        .doc("Right operand")
78        .example("4")
79        .take(args)
80        .then(|a| a.value().parse())?;
81
82    if args.metadata().help_mode {
83        return Ok(true);
84    }
85
86    let total = left + right;
87    for _ in 0..repeat {
88        println!("{total}");
89    }
90    Ok(true)
91}
More examples
Hide additional examples
examples/arrays.rs (line 20)
1fn main() -> noargs::Result<()> {
2    let mut args = noargs::raw_args();
3    args.metadata_mut().app_name = env!("CARGO_PKG_NAME");
4    args.metadata_mut().app_description = env!("CARGO_PKG_DESCRIPTION");
5
6    if noargs::VERSION_FLAG.take(&mut args).is_present() {
7        println!("{} {}", env!("CARGO_PKG_NAME"), env!("CARGO_PKG_VERSION"));
8        return Ok(());
9    }
10    noargs::HELP_FLAG.take_help(&mut args);
11
12    // Same-name options can be collected by calling take() in a loop.
13    let include_opt = noargs::opt("include")
14        .short('I')
15        .ty("PATH")
16        .doc("Include path (can be specified multiple times)");
17    let mut includes = Vec::<String>::new();
18    while let Some(path) = include_opt
19        .take(&mut args)
20        .present_and_then(|o| o.value().parse())?
21    {
22        includes.push(path);
23    }
24
25    let label_opt = noargs::opt("label")
26        .short('l')
27        .ty("LABEL")
28        .doc("Label value (can be specified multiple times)");
29    let mut labels = Vec::<String>::new();
30    while let Some(label) = label_opt
31        .take(&mut args)
32        .present_and_then(|o| o.value().parse())?
33    {
34        labels.push(label);
35    }
36
37    let output: String = noargs::opt("output")
38        .short('o')
39        .ty("PATH")
40        .doc("Output path")
41        .default("summary.txt")
42        .take(&mut args)
43        .then(|o| o.value().parse())?;
44
45    // Positional arrays are handled with one required argument + optional rest.
46    // Naming convention: use `<NAME>...` for required-many and `[NAME]...` for optional-many.
47    // The `<>` / `[]` / `...` markers are cosmetic (used only in help output);
48    // required-ness is enforced below: `.then()` makes the first input required,
49    // the loop with `.present_and_then()` consumes zero or more rest inputs.
50    let first_input: String = noargs::arg("<INPUT>")
51        .doc("First input (required)")
52        .example("a.txt")
53        .take(&mut args)
54        .then(|a| a.value().parse())?;
55    let rest_input_arg = noargs::arg("[INPUT]...").doc("Additional inputs");
56    let mut inputs = vec![first_input];
57    while let Some(input) = rest_input_arg
58        .take(&mut args)
59        .present_and_then(|a| a.value().parse())?
60    {
61        inputs.push(input);
62    }
63
64    if let Some(help) = args.finish()? {
65        print!("{help}");
66        return Ok(());
67    }
68
69    println!("includes={includes:?}");
70    println!("labels={labels:?}");
71    println!("inputs={inputs:?}");
72    println!("output={output}");
73    Ok(())
74}
examples/basics.rs (line 34)
1fn main() -> noargs::Result<()> {
2    let mut args = noargs::raw_args();
3    args.metadata_mut().app_name = env!("CARGO_PKG_NAME");
4    args.metadata_mut().app_description = env!("CARGO_PKG_DESCRIPTION");
5
6    if noargs::VERSION_FLAG.take(&mut args).is_present() {
7        println!("{} {}", env!("CARGO_PKG_NAME"), env!("CARGO_PKG_VERSION"));
8        return Ok(());
9    }
10    noargs::HELP_FLAG.take_help(&mut args);
11
12    // Important: call flag()/opt() before arg().
13    // Otherwise values like "-v" — or any unknown "--bogus" — can be silently
14    // consumed as positional arguments.
15    //
16    // Required option / positional: set example("...") so help mode renders
17    // a meaningful Usage / Example line. Optional fields covered by default()
18    // or present_and_then() do not need example().
19    let verbose = noargs::flag("verbose")
20        .short('v')
21        .doc("Enable verbose output")
22        .take(&mut args)
23        .is_present();
24    let dry_run = noargs::flag("dry-run")
25        .doc("Print parsed values and exit without running processing")
26        .take(&mut args)
27        .is_present();
28    let retries: usize = noargs::opt("retries")
29        .short('r')
30        .ty("N")
31        .doc("How many times to retry")
32        .default("1")
33        .take(&mut args)
34        .then(|o| o.value().parse())?;
35    let endpoint: String = noargs::opt("endpoint")
36        .ty("URL")
37        .doc("Server endpoint")
38        .env("NOARGS_ENDPOINT")
39        .default("http://localhost:8080")
40        .take(&mut args)
41        .then(|o| o.value().parse())?;
42    let format: String = noargs::opt("format")
43        .ty("FORMAT")
44        .doc("Output format")
45        .example("json")
46        .take(&mut args)
47        .then(|o| o.value().parse())?;
48    let timeout_secs: Option<u64> = noargs::opt("timeout")
49        .ty("SECONDS")
50        .doc("Optional timeout in seconds")
51        .take(&mut args)
52        .present_and_then(|o| o.value().parse())?;
53
54    let input: String = noargs::arg("<INPUT>")
55        .doc("Input file path")
56        .example("input.txt")
57        .take(&mut args)
58        .then(|a| a.value().parse())?;
59    // Optional positional with default(): the value is always a String —
60    // absent uses "out.txt", present uses the given path.
61    // For "absent vs present" distinction, use present_and_then() and bind
62    // to Option<String> — see the README's [BAZ] example.
63    let output: String = noargs::arg("[OUTPUT]")
64        .doc("Output file path")
65        .default("out.txt")
66        .take(&mut args)
67        .then(|a| a.value().parse())?;
68
69    if let Some(help) = args.finish()? {
70        // When help is requested, finish() returns the built help text.
71        // Print it here and exit without running application logic.
72        print!("{help}");
73        return Ok(());
74    }
75
76    if dry_run {
77        println!(
78            "dry-run: verbose={verbose}, retries={retries}, endpoint={endpoint}, format={format}, timeout_secs={timeout_secs:?}, input={input}, output={output}"
79        );
80        return Ok(());
81    }
82
83    println!("processing: {input} -> {output}");
84    println!("using endpoint={endpoint}, format={format}, retries={retries}");
85    if verbose {
86        println!("verbose: timeout_secs={timeout_secs:?}");
87    }
88
89    Ok(())
90}
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pub fn index(&self) -> Option<usize>

Returns the index at which the raw value associated with the name of this option was located in RawArgs.

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impl Clone for Opt

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fn clone(&self) -> Opt

Returns a duplicate of the value. Read more
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fn clone_from(&mut self, source: &Self)

Performs copy-assignment from source. Read more
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impl Debug for Opt

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fn fmt(&self, f: &mut Formatter<'_>) -> Result

Formats the value using the given formatter. Read more
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impl Hash for Opt

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fn hash<__H: Hasher>(&self, state: &mut __H)

Feeds this value into the given Hasher. Read more
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fn hash_slice<H>(data: &[Self], state: &mut H)
where H: Hasher, Self: Sized,

Feeds a slice of this type into the given Hasher. Read more
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impl PartialEq for Opt

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fn eq(&self, other: &Opt) -> bool

Tests for self and other values to be equal, and is used by ==.
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fn ne(&self, other: &Rhs) -> bool

Tests for !=. The default implementation is almost always sufficient, and should not be overridden without very good reason.
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impl Eq for Opt

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impl StructuralPartialEq for Opt

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impl Freeze for Opt

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impl RefUnwindSafe for Opt

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impl Send for Opt

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impl Sync for Opt

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impl Unpin for Opt

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impl UnsafeUnpin for Opt

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impl UnwindSafe for Opt

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impl<T> Any for T
where T: 'static + ?Sized,

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fn type_id(&self) -> TypeId

Gets the TypeId of self. Read more
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impl<T> Borrow<T> for T
where T: ?Sized,

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fn borrow(&self) -> &T

Immutably borrows from an owned value. Read more
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impl<T> BorrowMut<T> for T
where T: ?Sized,

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fn borrow_mut(&mut self) -> &mut T

Mutably borrows from an owned value. Read more
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impl<T> CloneToUninit for T
where T: Clone,

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unsafe fn clone_to_uninit(&self, dest: *mut u8)

🔬This is a nightly-only experimental API. (clone_to_uninit)
Performs copy-assignment from self to dest. Read more
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impl<T> From<T> for T

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fn from(t: T) -> T

Returns the argument unchanged.

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impl<T, U> Into<U> for T
where U: From<T>,

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fn into(self) -> U

Calls U::from(self).

That is, this conversion is whatever the implementation of From<T> for U chooses to do.

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impl<T> ToOwned for T
where T: Clone,

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type Owned = T

The resulting type after obtaining ownership.
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fn to_owned(&self) -> T

Creates owned data from borrowed data, usually by cloning. Read more
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fn clone_into(&self, target: &mut T)

Uses borrowed data to replace owned data, usually by cloning. Read more
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impl<T, U> TryFrom<U> for T
where U: Into<T>,

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type Error = Infallible

The type returned in the event of a conversion error.
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fn try_from(value: U) -> Result<T, <T as TryFrom<U>>::Error>

Performs the conversion.
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impl<T, U> TryInto<U> for T
where U: TryFrom<T>,

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type Error = <U as TryFrom<T>>::Error

The type returned in the event of a conversion error.
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fn try_into(self) -> Result<U, <U as TryFrom<T>>::Error>

Performs the conversion.