code review notes

close / do_close in result_set
avoid closing statements
remove named arguments
refactor positioned arguments query

src/db/connection.cr

@@ -15,15 +15,17 @@ module DB
   # Also override `#last_insert_id` to allow safe access to the last inserted id through this connection.
   #
   abstract class Connection
-    getter connection_string
+    # TODO add IDLE status, for connection ppool management.
 
-    def initialize(@connection_string)
-      @closed = false
+    getter connection_string # TODO Remove
+    @closed = false
+
+    def initialize(@connection_string) # TODO Remove
     end
 
     # Closes this connection.
     def close
-      raise "Connection already closed" if @closed
+      raise "Connection already closed" if @closed # TODO make it no fail if closed
       @closed = true
       perform_close
     end
@@ -44,8 +46,9 @@ module DB
     include QueryMethods
 
     # Returns the last inserted id through this connection.
-    abstract def last_insert_id : Int64
+    abstract def last_insert_id : Int64 # TODO move to ExecResult record. plano. with last_rows. eagerly askit.
 
-    protected abstract def perform_close
+
+    protected abstract def perform_close # TODO do_close
   end
 end

src/db/database.cr

@@ -24,8 +24,7 @@ module DB
       @connection.close
     end
 
-    # Returns a `Connection` to the database.
-    # Useful if you need to ensure the statements are executed in the connection.
+    # :nodoc:
     def connection
       @connection
     end

src/db/db.cr

@@ -64,10 +64,11 @@ module DB
   # method to be used as query parameters
   TYPES = [String, Int32, Int64, Float32, Float64, Slice(UInt8)]
 
-  # See `DB::TYPES` in `DB`
-  alias Any = String | Int32 | Int64 | Float32 | Float64 | Slice(UInt8)
+  # See `DB::TYPES` in `DB`. `Any` is a nillable version of the union of all types in `DB::TYPES`
+  alias Any = Nil | String | Int32 | Int64 | Float32 | Float64 | Slice(UInt8)
 
   # :nodoc:
+
   def self.driver_class(driver_name) # : Driver.class
     @@drivers.not_nil![driver_name]
   end

src/db/query_methods.cr

@@ -45,6 +45,8 @@ module DB
       prepare(query).scalar(*args)
     end
 
+    # TODO remove scalar?  make it always nillable. raise if 0-rows   raise +1-rows
+
     # Performs the `query` and returns a single scalar value of type `t`.
     # `t` must be any of the allowed `DB::Any` types.
     #

src/db/result_set.cr

@@ -13,12 +13,13 @@ module DB
   # 4. Override `#column_count`, `#column_name`.
   # 5. Override `#column_type`. It must return a type in `DB::TYPES`.
   abstract class ResultSet
-    # :nodoc:
     getter statement
 
     def initialize(@statement : Statement)
     end
 
+    # TODO add_next_result_set : Bool
+
     # Iterates over all the rows
     def each
       while move_next
@@ -26,9 +27,24 @@ module DB
       end
     end
 
-    # Closes the result set.
+    # Closes this result set.
     def close
-      @statement.close
+      return if @closed
+      @closed = true
+      do_close
+    end
+
+    # Returns `true` if this result set is closed. See `#close`.
+    def closed?
+      @closed
+    end
+
+    # :nodoc:
+    def finalize
+      close
+    end
+
+    protected def do_close
     end
 
     # Ensures it executes the query
@@ -65,5 +81,13 @@ module DB
         read?({{t}}).not_nil!
       end
     {% end %}
+
+    # def read_blob
+    #   yield ... io ....
+    # end
+
+    # def read_text
+    #   yield ... io ....
+    # end
   end
 end

src/db/statement.cr

@@ -72,35 +72,20 @@ module DB
       end
     end
 
+    private def execute : ResultSet
+      perform(Slice(Any).new(0))
+    end
+
     private def execute(*args) : ResultSet
-      execute args
-    end
-
-    private def execute(arg : Slice(UInt8))
-      begin_parameters
-      add_parameter 0, arg
-      perform
-    end
-
-    private def execute(args : Enumerable)
-      begin_parameters
-      args.each_with_index do |arg, index|
-        if arg.is_a?(Hash)
-          arg.each do |key, value|
-            add_parameter key.to_s, value
-          end
-        else
-          add_parameter index, arg
-        end
-      end
-      perform
+      # TODO better way to do it
+      perform(args.to_a.to_unsafe.to_slice(args.size))
     end
 
     # Closes this statement.
     def close
-      raise "Statement already closed" if @closed
+      return if @closed # make it work if closed
       @closed = true
-      on_close
+      do_close
     end
 
     # Returns `true` if this statement is closed. See `#close`.
@@ -108,19 +93,14 @@ module DB
       @closed
     end
 
-    # # :nodoc:
-    # def finalize
-    #   close unless closed?
-    # end
-
-    # 0-based positional arguments
-    protected def begin_parameters
+    # :nodoc:
+    def finalize
+      close
     end
-    protected abstract def add_parameter(index : Int32, value)
-    protected abstract def add_parameter(name : String, value)
 
-    protected abstract def perform : ResultSet
-    protected def on_close
+    protected abstract def perform(args : Slice(Any)) : ResultSet
+
+    protected def do_close
     end
   end
 end