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<a name="Transmitting-Dynamic-Structure"></a>
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<a name="Transmitting-Dynamic-Structure-1"></a>
<h4 class="subsubsection">8.1.5.3 Transmitting Dynamic Structure</h4>

<div class="smallexample">
<pre class="smallexample">

<b>with</b> Ada.Streams; <b>use</b> Ada.Streams;
<b>package</b> StringArrayStream <b>is</b>
   <b>pragma</b> Remote_Types;

   <b>type</b> List <b>is</b> <b>private</b>;
   <b>procedure</b> Append (L : <b>access</b> List; O : <b>in</b> String);
   <b>function</b>  Delete (L : <b>access</b> List) <b>return</b> String;

<b>private</b>
   --  implementation removed
<b>end</b> StringArrayStream;

</pre></div>

<p>Non-remote access types cannot be declared in the public part of a
remote types unit. However, it is possible to define private non-remote
access types as long as the user provides its marshalling procedures,
that is to say the mechanism needed to place a value of the type into a
communication stream.  The code below describes how to transmit a linked
structure.
</p>
<p>The package declaration provides a type definition of single-linked
lists of unbounded strings. An implementation of the marshalling
operations could be the following:
</p>
<div class="smallexample">
<pre class="smallexample">

<b>package</b> <b>body</b> StringArrayStream <b>is</b>
   <b>procedure</b> Read
     (S : <b>access</b> Root_Stream_Type'Class;
      L : <b>out</b> List) <b>is</b>
   <b>begin</b>
      <b>if</b> Boolean'Input (S) <b>then</b>
         L := <b>new</b> Node;
         L.Content := <b>new</b> String'(String'Input (S));
         List'Read (S, L.Next);
      <b>else</b>
         L := <b>null</b>;
      <b>end</b> <b>if</b>;
   <b>end</b> Read;

   <b>procedure</b> Write
     (S : <b>access</b> Root_Stream_Type'Class;
      L : <b>in</b> List) <b>is</b>
   <b>begin</b>
      <b>if</b> L = <b>null</b> <b>then</b>
         Boolean'Output (S, False);
      <b>else</b>
         Boolean'Output (S, True);
         String'Output (S, L.Content.<b>all</b>);
         List'Write (S, L.Next);
      <b>end</b> <b>if</b>;
   <b>end</b> Write;

   --  [...] Other services
<b>end</b> StringArrayStream;

</pre></div>





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