observable-property 0.4.3

A thread-safe observable property implementation for Rust
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
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135

use observable_property::{computed, ObservableProperty};
use std::sync::Arc;
use std::thread;
use std::time::Duration;

fn main() -> Result<(), observable_property::PropertyError> {
    println!("=== Computed Properties Example ===\n");

    // Example 1: Simple math computation
    println!("1. Rectangle Area Computation:");
    let width = Arc::new(ObservableProperty::new(10));
    let height = Arc::new(ObservableProperty::new(5));

    let area = computed(vec![width.clone(), height.clone()], |values| {
        values[0] * values[1]
    })?;

    // Subscribe to changes in the computed property
    area.subscribe(Arc::new(|old, new| {
        println!("   Area changed: {} -> {}", old, new);
    }))?;

    println!("   Initial area: {}", area.get()?);
    
    width.set(20)?;
    thread::sleep(Duration::from_millis(10));
    println!("   After width=20: {}", area.get()?);

    height.set(8)?;
    thread::sleep(Duration::from_millis(10));
    println!("   After height=8: {}", area.get()?);

    // Example 2: String concatenation
    println!("\n2. Full Name Computation:");
    let first_name = Arc::new(ObservableProperty::new("John".to_string()));
    let last_name = Arc::new(ObservableProperty::new("Doe".to_string()));

    let full_name = computed(
        vec![first_name.clone(), last_name.clone()],
        |values| format!("{} {}", values[0], values[1]),
    )?;

    full_name.subscribe(Arc::new(|_old, new| {
        println!("   Full name updated: {}", new);
    }))?;

    println!("   Initial name: {}", full_name.get()?);
    
    first_name.set("Jane".to_string())?;
    thread::sleep(Duration::from_millis(10));

    last_name.set("Smith".to_string())?;
    thread::sleep(Duration::from_millis(10));

    // Example 3: Price with tax computation
    println!("\n3. Total Price with Tax:");
    let subtotal = Arc::new(ObservableProperty::new(100.0_f64));
    let tax_rate = Arc::new(ObservableProperty::new(0.08_f64)); // 8% tax

    let total = computed(
        vec![subtotal.clone(), tax_rate.clone()],
        |values| values[0] * (1.0 + values[1]),
    )?;

    total.subscribe(Arc::new(|old, new| {
        println!("   Total price changed: ${:.2} -> ${:.2}", old, new);
    }))?;

    println!("   Initial total: ${:.2}", total.get()?);
    
    subtotal.set(200.0)?;
    thread::sleep(Duration::from_millis(10));

    tax_rate.set(0.10)?; // Change to 10%
    thread::sleep(Duration::from_millis(10));

    // Example 4: Multiple dependencies
    println!("\n4. Expression: a + b * c");
    let a = Arc::new(ObservableProperty::new(1));
    let b = Arc::new(ObservableProperty::new(2));
    let c = Arc::new(ObservableProperty::new(3));

    let result = computed(
        vec![a.clone(), b.clone(), c.clone()],
        |values| values[0] + values[1] * values[2],
    )?;

    result.subscribe(Arc::new(|old, new| {
        println!("   Result changed: {} -> {}", old, new);
    }))?;

    println!("   Initial: 1 + 2 * 3 = {}", result.get()?);
    
    a.set(5)?;
    thread::sleep(Duration::from_millis(10));
    println!("   After a=5: 5 + 2 * 3 = {}", result.get()?);

    b.set(4)?;
    thread::sleep(Duration::from_millis(10));
    println!("   After b=4: 5 + 4 * 3 = {}", result.get()?);

    // Example 5: Chained computed properties
    println!("\n5. Temperature Conversions:");
    let celsius = Arc::new(ObservableProperty::new(0.0_f64));

    let fahrenheit = computed(vec![celsius.clone()], |values| {
        values[0] * 9.0 / 5.0 + 32.0
    })?;

    let kelvin = computed(vec![celsius.clone()], |values| values[0] + 273.15)?;

    celsius.subscribe(Arc::new(|_, new| {
        println!("   Celsius updated: {:.1}°C", new);
    }))?;

    fahrenheit.subscribe(Arc::new(|_, new| {
        println!("   Fahrenheit updated: {:.1}°F", new);
    }))?;

    kelvin.subscribe(Arc::new(|_, new| {
        println!("   Kelvin updated: {:.2}K", new);
    }))?;

    println!("   Initial: {:.1}°C = {:.1}°F = {:.2}K", 
             celsius.get()?, fahrenheit.get()?, kelvin.get()?);

    celsius.set(100.0)?;
    thread::sleep(Duration::from_millis(10));

    celsius.set(-40.0)?;
    thread::sleep(Duration::from_millis(10));

    println!("\n=== Example Complete ===");
    Ok(())
}