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Adding examples for deriving Debug and Display. #424

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1d016e9
Adding examples for deriving Debug and Display.
plauche Jul 6, 2018
3c442d4
Updated dictionary.
plauche Jul 9, 2018
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6 changes: 6 additions & 0 deletions ci/dictionary.txt
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Original file line number Diff line number Diff line change
Expand Up @@ -14,6 +14,7 @@ AlphaNumeric
ApiResponse
Appender
appender
armv
args
ascii
ashley
Expand Down Expand Up @@ -80,6 +81,7 @@ dotfiles
DynamicImage
endian
endif
enum
EnvLogger
EnvVar
eprintln
Expand All @@ -91,6 +93,7 @@ filename
filenames
filepath
filesystem
FileType
FilterType
FixedOffset
flate
Expand Down Expand Up @@ -153,6 +156,7 @@ JSON
Json
json
julia
KeyPress
lang
LevelFilter
libhello
Expand Down Expand Up @@ -191,6 +195,7 @@ NotFound
NulError
OAuth
oneline
PageLoad
ParallelIterator
parallelized
params
Expand Down Expand Up @@ -315,6 +320,7 @@ vreq
WalkDir
Walkdir
walkdir
WebEvent
webpage
webservice
whitespace
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107 changes: 107 additions & 0 deletions src/basics.md
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Expand Up @@ -10,6 +10,8 @@
| [Generate random values of a custom type][ex-rand-custom] | [![rand-badge]][rand] | [![cat-science-badge]][cat-science] |
| [Create random passwords from a set of alphanumeric characters][ex-rand-passwd] | [![rand-badge]][rand] | [![cat-os-badge]][cat-os] |
| [Create random passwords from a set of user-defined characters][ex-rand-choose] | [![rand-badge]][rand] | [![cat-os-badge]][cat-os] |
| [Implement Debug for a custom type][ex-impl-debug] | [![std-badge]][std] | [![cat-os-badge]][cat] |
| [Implement Display for a custom type][ex-impl-display] | [![std-badge]][std] | [![cat-os-badge]][cat-os] |
| [Run an external command and process stdout][ex-parse-subprocess-output] | [![regex-badge]][regex] | [![cat-os-badge]][cat-os] [![cat-text-processing-badge]][cat-text-processing] |
| [Run an external command passing it stdin and check for an error code][ex-parse-subprocess-input] | [![regex-badge]][regex] | [![cat-os-badge]][cat-os] [![cat-text-processing-badge]][cat-text-processing] |
| [Run piped external commands][ex-run-piped-external-commands] | [![std-badge]][std] | [![cat-os-badge]][cat-os] |
Expand Down Expand Up @@ -1770,6 +1772,110 @@ fn run() -> Result<()> {
# quick_main!(run);
```

[ex-impl-debug]: #ex-impl-debug
<a name="ex-impl-debug"></a>
## Implementing Debug for a custom type

[![std-badge]][std] [![cat-os-badge]][cat-os]

Manually implements the [`Debug`] trait for a custom enum and it's attributes.

```rust
use std::fmt;

enum FileType {
Image {
format: String,
width: i32,
height: i32,
},
Text {
format: String,
},
Binary {
arch: String,
},
}

impl fmt::Debug for FileType {
fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
match self {
FileType::Image {
format,
width,
height,
} => write!(
f,
"Image {{ format: {}, width: {}, height: {} }}",
format, width, height
),
FileType::Text { format } => write!(f, "Text {{ format: {} }}", format),
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We actually don't need to manually write out the Text { format: value } struct-like format here. There are methods on the fmt::Formatter like debug_struct that will do this for us and keep it consistent with what you get from #[derive(Debug)].

FileType::Binary { arch } => write!(f, "Binary {{ arch: {} }}", arch),
}
}
}

fn main() {
let i = FileType::Image {
format: "jpg".to_string(),
width: 10,
height: 10,
};
println!("The FileType is: {:?}", i);

let t = FileType::Text {
format: "csv".to_string(),
};
println!("The FileType is: {:?}", t);

let b = FileType::Binary {
arch: "armv6".to_string(),
};
println!("The FileType is: {:?}", b);
}
```


[ex-impl-display]: #ex-impl-display
<a name="ex-impl-display"></a>
## Implementing Display for a custom type

[![std-badge]][std] [![cat-os-badge]][cat-os]

Manually implements the [`Display`] trait for a custom enum and it's attributes.

```rust
use std::fmt;

enum WebEvent {
PageLoad,
KeyPress(char),
Click { x: i64, y: i64 },
}

impl fmt::Display for WebEvent {
fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
match self {
WebEvent::PageLoad => write!(f, "PageLoad"),
WebEvent::KeyPress(c) => write!(f, "KeyPress({})", c),
WebEvent::Click { x, y } => write!(f, "Click(x: {}, y: {})", x, y),
}
}
}

fn main() {
let l = WebEvent::PageLoad;
println!("The WebEvent is: {}", l);

let k = WebEvent::KeyPress('K');
println!("The WebEvent is: {}", k);

let c = WebEvent::Click { x: 4, y: 9 };
println!("The WebEvent is: {}", c);
}
```


{{#include links.md}}

<!-- API Reference -->
Expand All @@ -1796,6 +1902,7 @@ fn run() -> Result<()> {
[`DateTime::to_rfc2822`]: https://docs.rs/chrono/*/chrono/struct.DateTime.html#method.to_rfc2822
[`DateTime::to_rfc3339`]: https://docs.rs/chrono/*/chrono/struct.DateTime.html#method.to_rfc3339
[`DateTime`]: https://docs.rs/chrono/*/chrono/struct.DateTime.html
[`Debug`]: https://doc.rust-lang.org/std/fmt/trait.Debug.html
[`digest::Context`]: https://briansmith.org/rustdoc/ring/digest/struct.Context.html
[`digest::Digest`]: https://briansmith.org/rustdoc/ring/digest/struct.Digest.html
[`DirEntry::path`]: https://doc.rust-lang.org/std/fs/struct.DirEntry.html#method.path
Expand Down
4 changes: 4 additions & 0 deletions src/intro.md
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Expand Up @@ -30,6 +30,8 @@ community. It needs and welcomes help. For details see
| [Create random passwords from a set of user-defined characters][ex-rand-choose] | [![rand-badge]][rand] | [![cat-os-badge]][cat-os] |
| [Run an external command and process stdout][ex-parse-subprocess-output] | [![regex-badge]][regex] | [![cat-os-badge]][cat-os] [![cat-text-processing-badge]][cat-text-processing] |
| [Run an external command passing it stdin and check for an error code][ex-parse-subprocess-input] | [![std-badge]][std] | [![cat-os-badge]][cat-os] |
| [Implement Debug for a custom type][ex-impl-debug] | [![std-badge]][std] | [![cat-os-badge]][cat-os] |
| [Implement Display for a custom type][ex-impl-display] | [![std-badge]][std] | [![cat-os-badge]][cat-os] |
| [Run piped external commands][ex-run-piped-external-commands] | [![std-badge]][std] | [![cat-os-badge]][cat-os] |
| [Redirect both stdout and stderr of child process to the same file][ex-redirect-stdout-stderr-same-file] | [![std-badge]][std] | [![cat-os-badge]][cat-os] |
| [Continuously process child process' outputs][ex-continuous-process-output] | [![std-badge]][std] | [![cat-os-badge]][cat-os][![cat-text-processing-badge]][cat-text-processing] |
Expand Down Expand Up @@ -204,6 +206,8 @@ community. It needs and welcomes help. For details see
[ex-global-mut-state]: basics.html#ex-global-mut-state
[ex-hex-encode-decode]: encoding.html#ex-hex-encode-decode
[ex-hmac]: basics.html#ex-hmac
[ex-impl-debug]: basics.html#ex-impl-debug
[ex-impl-display]: basics.html#ex-impl-display
[ex-invalid-csv]: encoding.html#ex-invalid-csv
[ex-json-value]: encoding.html#ex-json-value
[ex-lazy-constant]: basics.html#ex-lazy-constant
Expand Down