ExtensionDtype
==============

.. cpp:class:: pandas::ExtensionDtype

   Data type class for pandas extension types.

Example
-------

.. code-block:: cpp

   #include <pandas/pandas.h>
   using namespace pandas;

   // Use ExtensionDtype
   ExtensionDtype obj;
   // ... operations ...

Iteration
---------

.. list-table::
   :widths: 40 20 15 25
   :header-rows: 1

   * - Signature
     - Return Type
     - Location
     - Example
   * - ``virtual size_t itemsize() const = 0``
     - virtual size_t
     - pd_extension_dtype.h:42
     - 

Type Checking
-------------

.. list-table::
   :widths: 40 20 15 25
   :header-rows: 1

   * - Signature
     - Return Type
     - Location
     - Example
   * - ``virtual bool is_nullable() const``
     - virtual bool
     - pd_extension_dtype.h:55
     - 

Other Methods
-------------

.. list-table::
   :widths: 40 20 15 25
   :header-rows: 1

   * - Signature
     - Return Type
     - Location
     - Example
   * - ``virtual std::string kind() const = 0``
     - virtual std::string
     - pd_extension_dtype.h:49
     - :ref:`View <example-extensiondtype-kind-0>`
   * - ``virtual std::string name() const = 0``
     - virtual std::string
     - pd_extension_dtype.h:30
     - :ref:`View <example-extensiondtype-name-1>`
   * - ``virtual numpy::DType numpy_dtype() const = 0``
     - virtual numpy::DType
     - pd_extension_dtype.h:36
     - 
   * - ``virtual std::string repr() const``
     - virtual std::string
     - pd_extension_dtype.h:80
     - :ref:`View <example-extensiondtype-repr-2>`
   * - ``virtual const std::type_info& type() const = 0``
     - virtual const std::type_info&
     - pd_extension_dtype.h:61
     - :ref:`View <example-extensiondtype-type-3>`


Code Examples
-------------

The following examples are extracted from the test suite.

.. _example-extensiondtype-kind-0:

.. dropdown:: kind (pd_test_1_all.cpp:300)
   :class-title: example-dropdown

   .. code-block:: cpp
      :linenos:
      :lineno-start: 290
      :emphasize-lines: 11

      
          void pd_test_boolean_array_dtype() {
              std::cout << "========= BooleanArray: dtype ======================= ";
      
              pandas::BooleanArray arr;
              if (arr.dtype().name() != "boolean") {
                  std::cout << "  [FAIL] : in pd_test_boolean_array_dtype() : dtype name should be 'boolean'" << std::endl;
                  throw std::runtime_error("pd_test_boolean_array_dtype failed: dtype name");
              }
      
              if (arr.dtype().kind() != "b") {
                  std::cout << "  [FAIL] : in pd_test_boolean_array_dtype() : dtype kind should be 'b'" << std::endl;
                  throw std::runtime_error("pd_test_boolean_array_dtype failed: dtype kind");
              }
      
              std::cout << " -> tests passed" << std::endl;
          }
      }
      
      int pd_test_boolean_array_main() {
          std::cout << "====================================== running pd_test_boolean_array ==================================== " << std::endl;

.. _example-extensiondtype-name-1:

.. dropdown:: name (pd_test_1_all.cpp:295)
   :class-title: example-dropdown

   .. code-block:: cpp
      :linenos:
      :lineno-start: 285
      :emphasize-lines: 11

                  throw std::runtime_error("pd_test_boolean_array_reductions failed: mean");
              }
      
              std::cout << " -> tests passed" << std::endl;
          }
      
          void pd_test_boolean_array_dtype() {
              std::cout << "========= BooleanArray: dtype ======================= ";
      
              pandas::BooleanArray arr;
              if (arr.dtype().name() != "boolean") {
                  std::cout << "  [FAIL] : in pd_test_boolean_array_dtype() : dtype name should be 'boolean'" << std::endl;
                  throw std::runtime_error("pd_test_boolean_array_dtype failed: dtype name");
              }
      
              if (arr.dtype().kind() != "b") {
                  std::cout << "  [FAIL] : in pd_test_boolean_array_dtype() : dtype kind should be 'b'" << std::endl;
                  throw std::runtime_error("pd_test_boolean_array_dtype failed: dtype kind");
              }
      
              std::cout << " -> tests passed" << std::endl;

.. _example-extensiondtype-repr-2:

.. dropdown:: repr (pd_test_1_all.cpp:10906)
   :class-title: example-dropdown

   .. code-block:: cpp
      :linenos:
      :lineno-start: 10896
      :emphasize-lines: 11

          std::cout << " -> tests passed" << std::endl;
      }
      
      void pd_test_extension_index_repr() {
          std::cout << "========= repr =========================";
      
          pandas::CategoricalArray arr({"a", "b", "c"});
          // Use ExtensionIndex<CategoricalArray> directly to test base class repr
          pandas::ExtensionIndex<pandas::CategoricalArray> idx(arr, "test");
      
          std::string repr_str = idx.repr();
      
          bool passed = (!repr_str.empty() && repr_str.find("ExtensionIndex") != std::string::npos);
          if (!passed) {
              std::cout << "  [FAIL] : in pd_test_extension_index_repr() : repr check failed" << std::endl;
              throw std::runtime_error("pd_test_extension_index_repr failed");
          }
      
          std::cout << " -> tests passed" << std::endl;
      }
      

.. _example-extensiondtype-type-3:

.. dropdown:: type (pd_test_3_all.cpp:15450)
   :class-title: example-dropdown

   .. code-block:: cpp
      :linenos:
      :lineno-start: 15440
      :emphasize-lines: 11

      /**
       * Test Series.convert_dtypes() parameter flags
       */
      void pd_test_series_convert_dtypes_flags() {
          std::cout << "========= Series.convert_dtypes() flags =================";
      
          // Test convert_integer=false - with floats disabled too, so it becomes string/object
          pandas::Series<std::string> s({"1", "2", "3"}, "numbers");
          auto converted = s.convert_dtypes(true, true, false, true, false);  // convert_integer=false, convert_floating=false
      
          // Should remain object type (Series<std::string> has dtype_name()="object")
          // When integer and floating are both disabled for integer-like strings, it falls back to string type
          if (converted->dtype_name() != "object") {
              std::cout << "  [FAIL] : dtype should be object when convert_integer=false and convert_floating=false, got " << converted->dtype_name() << std::endl;
              throw std::runtime_error("pd_test_series_convert_dtypes_flags failed: convert_integer");
          }
      
          // Test convert_boolean=false - strings stay as object/string type
          pandas::Series<std::string> s_bool({"true", "false"}, "bools");
          auto converted_bool = s_bool.convert_dtypes(true, true, true, false, true);  // convert_boolean=false