TLV: README: use repetition numbers (#7114)

Author: Joe C

libraries/type-length-value/README.md

@@ -49,50 +49,56 @@ let account_size = TlvStateMut::get_base_len()
     + TlvStateMut::get_base_len()
     + std::mem::size_of::<MyOtherPodValue>()
     + TlvStateMut::get_base_len()
-    + std::mem::size_of::<MyOtherPodValue>()
+    + std::mem::size_of::<MyOtherPodValue>();
 
 // Buffer likely comes from a Solana `solana_program::account_info::AccountInfo`,
 // but this example just uses a vector.
 let mut buffer = vec![0; account_size];
 
-{
-    // Unpack the base buffer as a TLV structure
-    let mut state = TlvStateMut::unpack(&mut buffer).unwrap();
-    
-    // Init and write default value
-    // Note: you'll need to provide a boolean whether or not to allow repeating
-    // values with the same TLV discriminator.
-    // If set to false, this function will error when an existing entry is detected.
-    let (value, _) = state.init_value::<MyPodValue>(false).unwrap();
-    // Update it in-place
-    value.data[0] = 1;
-    
-    // Init and write another default value
-    // This time, we're going to allow repeating values.
-    let (other_value1, _) = state.init_value::<MyOtherPodValue>(true).unwrap();
-    assert_eq!(other_value1.data, 10);
-    // Update it in-place
-    other_value1.data = 2;
-    
-    // Let's do it again, since we can now have repeating values!
-    let (other_value2, _) = state.init_value::<MyOtherPodValue>(true).unwrap();
-    assert_eq!(other_value2.data, 10);
-    // Update it in-place
-    other_value2.data = 4;
-    
-    // Later on, to work with it again, we can just get the first value we
-    // encounter, because we did _not_ allow repeating entries for `MyPodValue`.
-    let value = state.get_first_value_mut::<MyPodValue>().unwrap();
-}
+// Unpack the base buffer as a TLV structure
+let mut state = TlvStateMut::unpack(&mut buffer).unwrap();
+
+// Init and write default value
+// Note: you'll need to provide a boolean whether or not to allow repeating
+// values with the same TLV discriminator.
+// If set to false, this function will error when an existing entry is detected.
+// Note the function also returns the repetition number, which can be used to
+// fetch the value again.
+let (value, _repetition_number) = state.init_value::<MyPodValue>(false).unwrap();
+// Update it in-place
+value.data[0] = 1;
+
+// Init and write another default value
+// This time, we're going to allow repeating values.
+let (other_value1, other_value1_repetition_number) =
+    state.init_value::<MyOtherPodValue>(true).unwrap();
+assert_eq!(other_value1.data, 10);
+// Update it in-place
+other_value1.data = 2;
+
+// Let's do it again, since we can now have repeating values!
+let (other_value2, other_value2_repetition_number) =
+    state.init_value::<MyOtherPodValue>(true).unwrap();
+assert_eq!(other_value2.data, 10);
+// Update it in-place
+other_value2.data = 4;
+
+// Later on, to work with it again, we can just get the first value we
+// encounter, because we did _not_ allow repeating entries for `MyPodValue`.
+let value = state.get_first_value_mut::<MyPodValue>().unwrap();
 
 // Or fetch it from an immutable buffer
 let state = TlvStateBorrowed::unpack(&buffer).unwrap();
 let value1 = state.get_first_value::<MyOtherPodValue>().unwrap();
 
 // Since we used repeating entries for `MyOtherPodValue`, we can grab either one by
-// its entry number
-let value1 = state.get_value_with_repetition::<MyOtherPodValue>(0).unwrap();
-let value2 = state.get_value_with_repetition::<MyOtherPodValue>(1).unwrap();
+// its repetition number
+let value1 = state
+    .get_value_with_repetition::<MyOtherPodValue>(other_value1_repetition_number)
+    .unwrap();
+let value2 = state
+    .get_value_with_repetition::<MyOtherPodValue>(other_value2_repetition_number)
+    .unwrap();
 
 ```