[GitHub] [arrow-rs] tustvold commented on a diff in pull request #2699: Clarify docs of binary and string builders

[GitBox <gi...@apache.org>]

tustvold commented on code in PR #2699:
URL: https://github.com/apache/arrow-rs/pull/2699#discussion_r967767856


##########
arrow/src/array/builder/generic_string_builder.rs:
##########
@@ -28,16 +28,17 @@ pub struct GenericStringBuilder<OffsetSize: OffsetSizeTrait> {
 }
 
 impl<OffsetSize: OffsetSizeTrait> GenericStringBuilder<OffsetSize> {
-    /// Creates a new [`GenericStringBuilder`],
+    /// Creates a new [`GenericStringBuilder`].
     pub fn new() -> Self {
         Self {
             builder: GenericBinaryBuilder::new(),
         }
     }
 
-    /// Creates a new [`GenericStringBuilder`],
-    /// `data_capacity` is the number of bytes of string data to pre-allocate space for in this builder
-    /// `item_capacity` is the number of items to pre-allocate space for in this builder
+    /// Creates a new [`GenericStringBuilder`].
+    ///
+    /// - `item_capacity` is the number of items to pre-allocate (the size of the buffer of offsets).

Review Comment:
   ```suggestion
       /// - `item_capacity` is the number of items to pre-allocate (i.e. the final length of the array).
   ```
   Or something, the offsets is actually one larger than this 😅



##########
arrow/src/array/builder/generic_binary_builder.rs:
##########
@@ -38,9 +38,10 @@ impl<OffsetSize: OffsetSizeTrait> GenericBinaryBuilder<OffsetSize> {
         Self::with_capacity(1024, 1024)
     }
 
-    /// Creates a new [`GenericBinaryBuilder`],
-    /// `item_capacity` is the number of items to pre-allocate space for in this builder
-    /// `data_capacity` is the number of bytes to pre-allocate space for in this builder
+    /// Creates a new [`GenericBinaryBuilder`].
+    ///
+    /// - `item_capacity` is the number of items to pre-allocate (the size of the buffer of offsets).

Review Comment:
   ```suggestion
       /// - `item_capacity` is the number of items to pre-allocate (i.e. the final length of the array).
   ```



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