bjoernager/rust
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Clean up Error Handling case study examples

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Remove unnecessary cloning and conversions. Expand tabs left in examples.
This commit is contained in:
Andrew Barchuk 2016-02-07 23:00:01 +02:00
parent f50fb159e9
commit 422cf2d34a
1 changed files with 44 additions and 45 deletions
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89
src/doc/book/error-handling.md
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@ -1592,7 +1592,7 @@ fn print_usage(program: &str, opts: Options) {
fn main() { fn main() {
let args: Vec<String> = env::args().collect(); let args: Vec<String> = env::args().collect();
let program = args[0].clone(); let program = &args[0];
let mut opts = Options::new(); let mut opts = Options::new();
opts.optflag("h", "help", "Show this usage message."); opts.optflag("h", "help", "Show this usage message.");
@ -1605,10 +1605,10 @@ fn main() {
print_usage(&program, opts); print_usage(&program, opts);
return; return;
} }
let data_path = args[1].clone(); let data_path = &args[1];
let city = args[2].clone(); let city = &args[2];
// Do stuff with information // Do stuff with information
} }
``` ```
@ -1640,7 +1640,6 @@ sure to add `extern crate csv;` to the top of your file.)
```rust,ignore ```rust,ignore
use std::fs::File; use std::fs::File;
use std::path::Path;
// This struct represents the data in each row of the CSV file. // This struct represents the data in each row of the CSV file.
// Type based decoding absolves us of a lot of the nitty gritty error // Type based decoding absolves us of a lot of the nitty gritty error
@ -1666,7 +1665,7 @@ fn print_usage(program: &str, opts: Options) {
fn main() { fn main() {
let args: Vec<String> = env::args().collect(); let args: Vec<String> = env::args().collect();
let program = args[0].clone(); let program = &args[0];
let mut opts = Options::new(); let mut opts = Options::new();
opts.optflag("h", "help", "Show this usage message."); opts.optflag("h", "help", "Show this usage message.");
@ -1678,25 +1677,24 @@ fn main() {
if matches.opt_present("h") { if matches.opt_present("h") {
print_usage(&program, opts); print_usage(&program, opts);
return; return;
} }
let data_file = args[1].clone(); let data_path = &args[1];
let data_path = Path::new(&data_file); let city: &str = &args[2];
let city = args[2].clone();
let file = File::open(data_path).unwrap(); let file = File::open(data_path).unwrap();
let mut rdr = csv::Reader::from_reader(file); let mut rdr = csv::Reader::from_reader(file);
for row in rdr.decode::<Row>() { for row in rdr.decode::<Row>() {
let row = row.unwrap(); let row = row.unwrap();
if row.city == city { if row.city == city {
println!("{}, {}: {:?}", println!("{}, {}: {:?}",
row.city, row.country, row.city, row.country,
row.population.expect("population count")); row.population.expect("population count"));
} }
} }
} }
``` ```
@ -1745,6 +1743,8 @@ Note that we opt to handle the possibility of a missing population count by
simply ignoring that row. simply ignoring that row.
```rust,ignore ```rust,ignore
use std::path::Path;
struct Row { struct Row {
// unchanged // unchanged
} }
@ -1782,27 +1782,26 @@ fn search<P: AsRef<Path>>(file_path: P, city: &str) -> Vec<PopulationCount> {
} }
fn main() { fn main() {
let args: Vec<String> = env::args().collect(); let args: Vec<String> = env::args().collect();
let program = args[0].clone(); let program = &args[0];
let mut opts = Options::new(); let mut opts = Options::new();
opts.optflag("h", "help", "Show this usage message."); opts.optflag("h", "help", "Show this usage message.");
let matches = match opts.parse(&args[1..]) { let matches = match opts.parse(&args[1..]) {
Ok(m) => { m } Ok(m) => { m }
Err(e) => { panic!(e.to_string()) } Err(e) => { panic!(e.to_string()) }
}; };
if matches.opt_present("h") { if matches.opt_present("h") {
print_usage(&program, opts); print_usage(&program, opts);
return; return;
} }
let data_file = args[1].clone(); let data_path = &args[1];
let data_path = Path::new(&data_file); let city = &args[2];
let city = args[2].clone(); for pop in search(data_path, city) {
for pop in search(&data_path, &city) { println!("{}, {}: {:?}", pop.city, pop.country, pop.count);
println!("{}, {}: {:?}", pop.city, pop.country, pop.count); }
}
} }
``` ```
@ -1912,7 +1911,7 @@ First, here's the new usage:
```rust,ignore ```rust,ignore
fn print_usage(program: &str, opts: Options) { fn print_usage(program: &str, opts: Options) {
println!("{}", opts.usage(&format!("Usage: {} [options] <city>", program))); println!("{}", opts.usage(&format!("Usage: {} [options] <city>", program)));
} }
``` ```
The next part is going to be only a little harder: The next part is going to be only a little harder:
@ -1924,16 +1923,16 @@ opts.optopt("f", "file", "Choose an input file, instead of using STDIN.", "NAME"
opts.optflag("h", "help", "Show this usage message."); opts.optflag("h", "help", "Show this usage message.");
... ...
let file = matches.opt_str("f"); let file = matches.opt_str("f");
let data_file = file.as_ref().map(Path::new); let data_file = &file.as_ref().map(Path::new);
let city = if !matches.free.is_empty() { let city = if !matches.free.is_empty() {
matches.free[0].clone() &matches.free[0]
} else { } else {
print_usage(&program, opts); print_usage(&program, opts);
return; return;
}; };
match search(&data_file, &city) { match search(data_file, city) {
Ok(pops) => { Ok(pops) => {
for pop in pops { for pop in pops {
println!("{}, {}: {:?}", pop.city, pop.country, pop.count); println!("{}, {}: {:?}", pop.city, pop.country, pop.count);