logcall 0.1.13

An attribute macro that logs the function return value.
Documentation 
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70

use logcall::logcall;
use logforth::append;
use logforth::filter::EnvFilter;

/// Logs the function call at the default `debug` level.
#[logcall]
fn add(a: i32, b: i32) -> i32 {
    a + b
}

/// Logs the function call at the `info` level.
#[logcall("info")]
fn multiply(a: i32, b: i32) -> i32 {
    a * b
}

/// Logs `Ok` results at the `info` level and `Err` results at the `error` level.
#[logcall(ok = "info", err = "error")]
fn divide(a: i32, b: i32) -> Result<i32, String> {
    if b == 0 {
        Err("Division by zero".to_string())
    } else {
        Ok(a / b)
    }
}

/// Logs errors at the `error` level. No log output for `Ok` variant.
#[logcall(err = "error")]
fn divide2(a: usize, b: usize) -> Result<usize, String> {
    if b == 0 {
        Err("Division by zero".to_string())
    } else {
        Ok(a / b)
    }
}

/// Logs the function call with custom input logging format.
#[logcall(input = "a = {a:?}, ..")]
fn subtract(a: i32, b: i32) -> i32 {
    a - b
}

/// Logs the function call with custom output logging format.
#[logcall(output = ": {:?}")]
fn negate(a: i32) -> i32 {
    -a
}

/// Omits the return value from the log output.
#[logcall(output = "")]
fn ping(a: i32) -> i32 {
    a
}

fn main() {
    logforth::builder()
        .dispatch(|d| {
            d.filter(EnvFilter::from_default_env_or("trace"))
                .append(append::Stderr::default())
        })
        .apply();

    add(2, 3);
    multiply(2, 3);
    divide(2, 0).ok();
    divide2(2, 0).ok();
    subtract(3, 2);
    negate(5);
    ping(42);
}