refactor: rename PendingUpdateBase to PendingUpdate for cleaner API

Renamed:
- PendingUpdateBase -> PendingUpdate (non-template base class)
- PendingUpdate<T> -> PendingUpdateTyped<T> (template class)

This makes the API more intuitive:
std::vector<std::unique_ptr<PendingUpdate>> is cleaner than
std::vector<std::unique_ptr<PendingUpdateBase>>

Author: shangxinli

src/iceberg/pending_update.h

@@ -28,17 +28,17 @@
 
 namespace iceberg {
 
-/// \brief Non-template base class for table metadata changes using builder pattern
+/// \brief Base class for table metadata changes using builder pattern
 ///
 /// This base class allows storing different types of PendingUpdate operations
 /// in the same collection (e.g., in Transaction). It provides the common Commit()
 /// interface that all updates share.
 ///
 /// This matches the Java Iceberg pattern where BaseTransaction stores a
 /// List<PendingUpdate> without type parameters.
-class ICEBERG_EXPORT PendingUpdateBase {
+class ICEBERG_EXPORT PendingUpdate {
  public:
-  virtual ~PendingUpdateBase() = default;
+  virtual ~PendingUpdate() = default;
 
   /// \brief Apply and commit the pending changes to the table
   ///
@@ -53,18 +53,18 @@ class ICEBERG_EXPORT PendingUpdateBase {
   virtual Status Commit() = 0;
 
   // Non-copyable, movable
-  PendingUpdateBase(const PendingUpdateBase&) = delete;
-  PendingUpdateBase& operator=(const PendingUpdateBase&) = delete;
-  PendingUpdateBase(PendingUpdateBase&&) noexcept = default;
-  PendingUpdateBase& operator=(PendingUpdateBase&&) noexcept = default;
+  PendingUpdate(const PendingUpdate&) = delete;
+  PendingUpdate& operator=(const PendingUpdate&) = delete;
+  PendingUpdate(PendingUpdate&&) noexcept = default;
+  PendingUpdate& operator=(PendingUpdate&&) noexcept = default;
 
  protected:
-  PendingUpdateBase() = default;
+  PendingUpdate() = default;
 };
 
 /// \brief Template class for type-safe table metadata changes using builder pattern
 ///
-/// PendingUpdate extends PendingUpdateBase with a type-safe Apply() method that
+/// PendingUpdateTyped extends PendingUpdate with a type-safe Apply() method that
 /// returns the specific result type for each operation. Subclasses implement
 /// specific types of table updates such as schema changes, property updates, or
 /// snapshot-producing operations like appends and deletes.
@@ -74,9 +74,9 @@ class ICEBERG_EXPORT PendingUpdateBase {
 ///
 /// \tparam T The type of result returned by Apply()
 template <typename T>
-class ICEBERG_EXPORT PendingUpdate : public PendingUpdateBase {
+class ICEBERG_EXPORT PendingUpdateTyped : public PendingUpdate {
  public:
-  ~PendingUpdate() override = default;
+  ~PendingUpdateTyped() override = default;
 
   /// \brief Apply the pending changes and return the uncommitted result
   ///
@@ -88,7 +88,7 @@ class ICEBERG_EXPORT PendingUpdate : public PendingUpdateBase {
   virtual Result<T> Apply() = 0;
 
  protected:
-  PendingUpdate() = default;
+  PendingUpdateTyped() = default;
 };
 
 }  // namespace iceberg

src/iceberg/test/pending_update_test.cc

@@ -29,7 +29,7 @@ namespace iceberg {
 // Mock implementation for testing the interface
 class MockSnapshot {};
 
-class MockPendingUpdate : public PendingUpdate<MockSnapshot> {
+class MockPendingUpdate : public PendingUpdateTyped<MockSnapshot> {
  public:
   MockPendingUpdate() = default;
 
@@ -91,7 +91,7 @@ TEST(PendingUpdateTest, CommitFailed) {
 }
 
 TEST(PendingUpdateTest, BaseClassPolymorphism) {
-  std::unique_ptr<PendingUpdateBase> base_ptr = std::make_unique<MockPendingUpdate>();
+  std::unique_ptr<PendingUpdate> base_ptr = std::make_unique<MockPendingUpdate>();
   auto status = base_ptr->Commit();
   EXPECT_THAT(status, IsOk());
 }

src/iceberg/type_fwd.h

@@ -154,9 +154,9 @@ class TableRequirement;
 class TableMetadataBuilder;
 class TableUpdateContext;
 
-class PendingUpdateBase;
-template <typename T>
 class PendingUpdate;
+template <typename T>
+class PendingUpdateTyped;
 
 /// ----------------------------------------------------------------------------
 /// TODO: Forward declarations below are not added yet.