today's savings

20-dev/00-rust/functional examples/Untitled.md

@@ -0,0 +1,56 @@
+```rust
+#[derive(Debug)]
+struct Person {
+    name: String,
+    age: u8,
+}
+
+impl Default for Person {
+    fn default() -> Self {
+        Self {
+            name: String::from("John"),
+            age: 30,
+        }
+    }
+}
+```
+
+```rust
+impl From<&str> for Person {
+    fn from(s: &str) -> Self {
+        s.split_once(',')
+            .filter(|(name, _)| !name.is_empty())
+            .and_then(|(name, age_str)| {
+                age_str.parse::<u8>().ok().map(|age| (name, age))
+            })
+            .map(|(name, age)| Person {
+                name: name.to_string(),
+                age,
+            })
+            .unwrap_or_default()
+    }
+}
+```
+
+как это написать через match:
+
+```rust
+impl From<&str> for Person {
+    fn from(s: &str) -> Self {
+        let Some((name, age_str)) = s.split_once(',') else {
+            return Person::default();
+        };
+        if name.is_empty() {
+            return Person::default();
+        }
+        let Ok(age) = age_str.parse::<u8>() else {
+            return Person::default();
+        };
+        Person {
+            name: name.to_string(),
+            age,
+        }
+    }
+}
+```
+