rust-error-handling — human mapping

Error handling improvement: Converted from panic-based error handling (unwrap()) to proper Result-based error handling using the ? operator. This is a common Rust refactoring pattern. Key changes: - Changed return type from `String` to `Result<String, std::io::Error>` - Replaced `.unwrap()` calls with `?` operator - Updated main function to return `Result<(), std::io::Error>` - Added proper error propagation This represents a typical Rust code quality improvement where error handling is made more robust.

This mapping has 3 multi-map groups: several pairings are equally correct there. The code view shows one arbitrary valid pairing, not the only one.

A painting is a person's account of this edit as text, recorded independently of the node mapping - a rendering often has several equally defensible answers where the mapping has one. Deletions and insertions carry no position on the opposite side in a painting, so that panel draws no caret for them.

Before1use std::fs::File;
2use std::io::Read;
3
4fn read_file(path: &str) -> String {
5    let mut file = File::open(path).unwrap();
6    let mut contents = String::new();
7    file.read_to_string(&mut contents).unwrap();
8    contents
9}
10
11fn main() {
12    let content = read_file("data.txt");
13    println!("File content: {}", content);
14}

After1use std::fs::File;
2use std::io::Read;
3
4fn read_file(path: &str) -> Result<String, std::io::Error> {
5    let mut file = File::open(path)?;
6    let mut contents = String::new();
7    file.read_to_string(&mut contents)?;
8    Ok(contents)
9}
10
11fn main() -> Result<(), std::io::Error> {
12    let content = read_file("data.txt")?;
13    println!("File content: {}", content);
14    Ok(())
15}

Before1use std::fs::File;
2use std::io::Read;
3
4fn read_file(path: &str) -> String {
5    let mut file = File::open(path).unwrap();
6    let mut contents = String::new();
7    file.read_to_string(&mut contents).unwrap();
8    contents
9}
10
11fn main() {
12    let content = read_file("data.txt");
13    println!("File content: {}", content);
14}

After1use std::fs::File;
2use std::io::Read;
3
4fn read_file(path: &str) -> Result<String, std::io::Error> {
5    let mut file = File::open(path)?;
6    let mut contents = String::new();
7    file.read_to_string(&mut contents)?;
8    Ok(contents)
9}
10
11fn main() -> Result<(), std::io::Error> {
12    let content = read_file("data.txt")?;
13    println!("File content: {}", content);
14    Ok(())
15}

Before1use std::fs::File;
2use std::io::Read;
3
4fn read_file(path: &str) -> String {
5    let mut file = File::open(path).unwrap();
6    let mut contents = String::new();
7    file.read_to_string(&mut contents).unwrap();
8    contents
9}
10
11fn main() {
12    let content = read_file("data.txt");
13    println!("File content: {}", content);
14}

After1use std::fs::File;
2use std::io::Read;
3
4fn read_file(path: &str) -> Result<String, std::io::Error> {
5    let mut file = File::open(path)?;
6    let mut contents = String::new();
7    file.read_to_string(&mut contents)?;
8    Ok(contents)
9}
10
11fn main() -> Result<(), std::io::Error> {
12    let content = read_file("data.txt")?;
13    println!("File content: {}", content);
14    Ok(())
15}

Before

source_file

use_declaration

use "use"

scoped_identifier

identifier "std"

:: "::"

identifier "fs"

:: "::"

identifier "File"

; ";"

use_declaration

use "use"

scoped_identifier

identifier "std"

:: "::"

identifier "io"

:: "::"

identifier "Read"

; ";"

function_item

fn "fn"

identifier "read_file"

parameters

( "("

parameter

identifier "path"

: ":"

reference_type

& "&"

primitive_type "str"

) ")"

-> "->"

type_identifier "String"

block

{ "{"

let_declaration

let "let"

mutable_specifier "mut"

identifier "file"

= "="

call_expression any 2:1

field_expression

call_expression any 2:1

scoped_identifier

identifier "File"

:: "::"

identifier "open"

arguments

( "("

identifier "path"

) ")"

. "."

field_identifier "unwrap"

arguments

( "("

) ")"

; ";"

let_declaration

let "let"

mutable_specifier "mut"

identifier "contents"

= "="

call_expression

scoped_identifier

identifier "String"

:: "::"

identifier "new"

arguments

( "("

) ")"

; ";"

expression_statement

call_expression any 2:1

field_expression any 2:1

call_expression any 2:1

field_expression any 2:1

identifier "file"

. "."

field_identifier "read_to_string"

arguments

( "("

reference_expression

& "&"

mutable_specifier "mut"

identifier "contents"

) ")"

. "."

field_identifier "unwrap"

arguments

( "("

) ")"

; ";"

identifier "contents"

} "}"

function_item

fn "fn"

identifier "main"

parameters

( "("

) ")"

block

{ "{"

let_declaration

let "let"

identifier "content"

= "="

call_expression

identifier "read_file"

arguments

( "("

string_literal

" "\""

string_content "data.txt"

" "\""

) ")"

; ";"

expression_statement

macro_invocation

identifier "println"

! "!"

token_tree

( "("

string_literal

" "\""

string_content "File content: {}"

" "\""

, ","

identifier "content"

) ")"

; ";"

} "}"

After

source_file

use_declaration

use "use"

scoped_identifier

identifier "std"

:: "::"

identifier "fs"

:: "::"

identifier "File"

; ";"

use_declaration

use "use"

scoped_identifier

identifier "std"

:: "::"

identifier "io"

:: "::"

identifier "Read"

; ";"

function_item

fn "fn"

identifier "read_file"

parameters

( "("

parameter

identifier "path"

: ":"

reference_type

& "&"

primitive_type "str"

) ")"

-> "->"

generic_type

type_identifier "Result"

type_arguments

< "<"

type_identifier "String"

, ","

scoped_type_identifier

scoped_identifier

identifier "std"

:: "::"

identifier "io"

:: "::"

type_identifier "Error"

> ">"

block

{ "{"

let_declaration

let "let"

mutable_specifier "mut"

identifier "file"

= "="

try_expression

call_expression any 2:1

scoped_identifier

identifier "File"

:: "::"

identifier "open"

arguments

( "("

identifier "path"

) ")"

? "?"

; ";"

let_declaration

let "let"

mutable_specifier "mut"

identifier "contents"

= "="

call_expression

scoped_identifier

identifier "String"

:: "::"

identifier "new"

arguments

( "("

) ")"

; ";"

expression_statement

try_expression

call_expression any 2:1

field_expression any 2:1

identifier "file"

. "."

field_identifier "read_to_string"

arguments

( "("

reference_expression

& "&"

mutable_specifier "mut"

identifier "contents"

) ")"

? "?"

; ";"

call_expression

identifier "Ok"

arguments

( "("

identifier "contents"

) ")"

} "}"

function_item

fn "fn"

identifier "main"

parameters

( "("

) ")"

-> "->"

generic_type

type_identifier "Result"

type_arguments

< "<"

unit_type

( "("

) ")"

, ","

scoped_type_identifier

scoped_identifier

identifier "std"

:: "::"

identifier "io"

:: "::"

type_identifier "Error"

> ">"

block

{ "{"

let_declaration

let "let"

identifier "content"

= "="

try_expression

call_expression

identifier "read_file"

arguments

( "("

string_literal

" "\""

string_content "data.txt"

" "\""

) ")"

? "?"

; ";"

expression_statement

macro_invocation

identifier "println"

! "!"

token_tree

( "("

string_literal

" "\""

string_content "File content: {}"

" "\""

, ","

identifier "content"

) ")"

; ";"

call_expression

identifier "Ok"

arguments

( "("

unit_expression

( "("

) ")"

} "}"