cb_ptr_fun_w_ret_example.htm

来自「The goal of this library is to make ODBC」· HTM 代码 · 共 40 行

<pre><code><span class="codeComment">//Simple use of cb_ptr_fun_w_ret() as a SelVal</span>



<span class="codeComment">// a typical SelVal function that we want to use in DTL
// an Example object is valid if all columns have a value</span>
bool ExampleSelValidate(boundIOs &amp;boundIOs, Example &amp;rowbuf)
{
	for (BoundIOs::iterator b_it = boundIOs.begin();
				b_it != boundIOs.end(); b_it++)
	{
		BoundIO &boundIO = (*b_it).second;
		if (boundIO.IsColumn() && boundIO.IsNull())
			return false;  <span class="codeComment">// found null column ... data is invalid</span>
	}

	return true;	<span class="codeComment">// no nulls found ... data is OK</span>
}

<span class="codeComment">// Read the contents of the DB_EXAMPLE table and return a vector of the
// resulting rows</span>
vector&lt;Example&gt; ReadData()
{
 vector&lt;Example&gt; results;

 <span class="codeComment">// the call to cb_ptr_fun_w_ret() wraps ExampleSelValidate in a function object
 // so DTL may use it as the SelVal for the DBView</span>
 DBView&lt;Example&gt; view(&quot;DB_EXAMPLE&quot;, DefaultBCA&lt;Example&gt;(),
	&quot;&quot;, DefaultBPA&lt;Example&gt;(), cb_ptr_fun_w_ret(ExampleSelValidate));

 DBView&lt;Example&gt;::select_iterator read_it = view.begin();
 for ( ; read_it != view.end(); ++read_it)
 {
  results.push_back(*read_it);
 }

 return results;
}

</code></pre>