From a74fb14ed04b0e6ef045ab7a25b9c0543b47e9e5 Mon Sep 17 00:00:00 2001
From: Daniel Frey <d.frey@gmx.de>
Date: Sat, 2 Mar 2024 00:22:38 +0100
Subject: [PATCH] Allow deriving from connection pools

---
 include/tao/pq/connection_pool.hpp | 10 ++++++++--
 src/lib/pq/connection_pool.cpp     |  5 -----
 2 files changed, 8 insertions(+), 7 deletions(-)

diff --git a/include/tao/pq/connection_pool.hpp b/include/tao/pq/connection_pool.hpp
index 0b7a785..ff0841c 100644
--- a/include/tao/pq/connection_pool.hpp
+++ b/include/tao/pq/connection_pool.hpp
@@ -21,7 +21,7 @@
 
 namespace tao::pq
 {
-   class connection_pool final
+   class connection_pool
       : public internal::pool< connection >
    {
    private:
@@ -29,6 +29,7 @@ namespace tao::pq
       std::optional< std::chrono::milliseconds > m_timeout;
       std::function< poll::callback > m_poll;
 
+   protected:
       [[nodiscard]] auto v_create() const -> std::unique_ptr< pq::connection > override;
 
       [[nodiscard]] auto v_is_valid( connection& c ) const noexcept -> bool override
@@ -36,6 +37,7 @@ namespace tao::pq
          return c.is_idle();
       }
 
+   private:
       // pass-key idiom
       class private_key final
       {
@@ -46,7 +48,11 @@ namespace tao::pq
    public:
       connection_pool( const private_key /*unused*/, const std::string_view connection_info, std::function< poll::callback > poll_cb );
 
-      [[nodiscard]] static auto create( const std::string_view connection_info, std::function< poll::callback > poll_cb = internal::poll ) -> std::shared_ptr< connection_pool >;
+      template< typename T = connection_pool >
+      [[nodiscard]] static auto create( const std::string_view connection_info, std::function< poll::callback > poll_cb = internal::poll ) -> std::shared_ptr< T >
+      {
+         return std::make_shared< T >( private_key(), connection_info, std::move( poll_cb ) );
+      }
 
       [[nodiscard]] auto timeout() const noexcept -> decltype( auto )
       {
diff --git a/src/lib/pq/connection_pool.cpp b/src/lib/pq/connection_pool.cpp
index 9371a05..c42f576 100644
--- a/src/lib/pq/connection_pool.cpp
+++ b/src/lib/pq/connection_pool.cpp
@@ -16,11 +16,6 @@ namespace tao::pq
         m_poll( std::move( poll_cb ) )
    {}
 
-   auto connection_pool::create( const std::string_view connection_info, std::function< poll::callback > poll_cb ) -> std::shared_ptr< connection_pool >
-   {
-      return std::make_shared< connection_pool >( private_key(), connection_info, std::move( poll_cb ) );
-   }
-
    void connection_pool::set_timeout( const std::chrono::milliseconds timeout ) noexcept
    {
       m_timeout = timeout;