Alexey Serbin has posted comments on this change.
Change subject: util: add Status::AndThen combinator
......................................................................
Patch Set 3: Code-Review+1
> Here's an example from a patch which builds off this, in
> CatalogManager::CreateTable
>
> // a. Validate the user request.
> Schema client_schema;
> s = SchemaFromPB(req.schema(), &client_schema)
> .AndThen([&] () {
> return ValidateIdentifier(req.database_name()).CloneAndPrepend("invalid
> database name");
> }).AndThen([&] () {
> return ValidateIdentifier(req.table_name()).CloneAndPrepend("invalid
> table name");
> }).AndThen([&] () {
> return ValidateClientSchema(client_schema);
> }).AndThen([&] () {
> if (client_schema.has_column_ids()) {
> return Status::InvalidArgument("user requests should not have
> Column IDs");
> } else {
> return Status::OK();
> }
> });
>
> if (!s.ok()) {
> return SetError(MasterErrorPB::INVALID_SCHEMA, s);
> }
>
>
> For what it's worth, this is a common method to have on status-like
> types in functional languages, for instance Scala's Try.flatMap[1]
> or Rust's Result.and_then [2].
>
> [1]:
> http://www.scala-lang.org/api/2.12.x/scala/util/Try.html#flatMap[U](f:T=>scala.util.Try[U]):scala.util.Try[U]
> [2]: https://doc.rust-lang.org/std/result/enum.Result.html#method.and_then
Thanks! I appreciate this.
For some reason I thought the rollback method somehow could be specified in the
AndThen() -- that was my misunderstanding.
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Gerrit-MessageType: comment
Gerrit-Change-Id: Ia6e1a79ff95406825d4238a8157d242252562805
Gerrit-PatchSet: 3
Gerrit-Project: kudu
Gerrit-Branch: master
Gerrit-Owner: Dan Burkert <[email protected]>
Gerrit-Reviewer: Alexey Serbin <[email protected]>
Gerrit-Reviewer: Dan Burkert <[email protected]>
Gerrit-Reviewer: Kudu Jenkins
Gerrit-Reviewer: Tidy Bot
Gerrit-Reviewer: Todd Lipcon <[email protected]>
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