alamb commented on code in PR #7865: URL: https://github.com/apache/arrow-rs/pull/7865#discussion_r2187106825
########## parquet-variant/src/builder.rs: ########## @@ -668,43 +739,41 @@ impl<'a, 'b> ObjectBuilder<'a, 'b> { self } - /// Return a new [`ObjectBuilder`] to add a nested object with the specified - /// key to the object. - pub fn new_object(&mut self, key: &'b str) -> ObjectBuilder { - self.check_pending_field(); - - let field_start = self.buffer.offset(); - let obj_builder = ObjectBuilder::new(&mut self.buffer, self.metadata_builder) - .with_validate_unique_fields(self.validate_unique_fields); - self.pending = Some((key, field_start)); - - obj_builder + // Returns validate_unique_fields because we can no longer reference self once this method returns. + fn parent_state<'b>(&'b mut self, key: &'b str) -> (ParentState<'b>, bool) { + let state = ParentState::Object { + buffer: &mut self.buffer, + metadata_builder: self.parent_state.metadata_builder(), + fields: &mut self.fields, + field_name: key, + }; + (state, self.validate_unique_fields) } - /// Return a new [`ListBuilder`] to add a list with the specified key to the - /// object. - pub fn new_list(&mut self, key: &'b str) -> ListBuilder { - self.check_pending_field(); - - let field_start = self.buffer.offset(); - let list_builder = ListBuilder::new(&mut self.buffer, self.metadata_builder) - .with_validate_unique_fields(self.validate_unique_fields); - self.pending = Some((key, field_start)); - - list_builder + /// Returns an object builder that can be used to append a new (nested) object to this list. + /// + /// WARNING: The builder will have no effect unless/until [`ObjectBuilder::finish`] is called. + pub fn new_object<'b>(&'b mut self, key: &'b str) -> ObjectBuilder<'b> { + let (parent_state, validate_unique_fields) = self.parent_state(key); + ObjectBuilder::new(parent_state, validate_unique_fields) } - /// Finalize object + /// Returns a list builder that can be used to append a new (nested) list to this list. /// - /// This consumes self and writes the object to the parent buffer. - pub fn finish(mut self) -> Result<(), ArrowError> { - self.check_pending_field(); + /// WARNING: The builder will have no effect unless/until [`ListBuilder::finish`] is called. + pub fn new_list<'b>(&'b mut self, key: &'b str) -> ListBuilder<'b> { + let (parent_state, validate_unique_fields) = self.parent_state(key); + ListBuilder::new(parent_state, validate_unique_fields) + } + /// Finalizes this object and appends it to its parent, which otherwise remains unmodified. + pub fn finish(mut self) -> Result<(), ArrowError> { + let metadata_builder = self.parent_state.metadata_builder(); Review Comment: > If so, this seems not resolve the issue @alamb raised at the beginning? Because I guess the case @alamb concern is like > > ``` > let mut builder = VariantBuilder::new(); > ... > { > let _object_builder = builder.new_object(); > _object_builder.insert(xxx); > _object_builder.insert(yyy); > _object_builder.insert(zzz); > // _object_builder doesn't been finalized. > } > ... > builder.finish(); > ``` My initial concern was that it was too easy to forget to call `finish` and thus lose the structure Along the way @scovich convinced me that this was acceptable (and actually preferrable) behavior rather than auto completing builders on drop THe rationale is that there are other ways that `drop` gets called other than forgetting to call `build` -- for example an exit on error when using `?` where the object probably *shouldn't* get dropped I think after this PR the behavior makes much more sense and is now documented -- This is an automated message from the Apache Git Service. To respond to the message, please log on to GitHub and use the URL above to go to the specific comment. To unsubscribe, e-mail: github-unsubscr...@arrow.apache.org For queries about this service, please contact Infrastructure at: us...@infra.apache.org