string $sSel[] = `ls -sl -dag -typ mesh`;	// Notice the use of -dag and -typ switches.
						// Normally you're only selecting transform nodes in the Maya view ports.
						// The -dag is used to list all the shape nodes (among other things) as well.
						// We're only interested in mesh objects so with the -typ mesh we'll limit the
						// ls command to list meshes only in the selection
int $iSize = size($sSel), $i;

if($iSize > 0)
{
	for($i = 0; $i < $iSize; $i++)
	{
		if($sSel[$i] == "myObjectShape")
		{
			// By looking in to the DG Node reference we know that the .dv attribute is a boolean.
			// However we define booleans as integers because there is no bool type in mel.

			int $bDv = `getAttr ($sSel[$i] + ".dv")`; // Now the $bDv variable contains the value of myObjectShape.dv

			// Let's find out if it's set
			if($bDv)
			{
				print("myObjectShape.dv is on\n");
				// <Do other stuff what needs to be done if the attribute is set>
			}
			else
			{
				print("myObjectShape.dv is off\n");
				// <Do other stuff what needs to be done if the attribute is not set>
			}
		}
		else
			warning("myObjectShape could not be found in the selection!\n");
	}
}
else
{
	warning("Nothing selected...\n");
}

string $sSel[] = `ls -sl -dag -typ mesh`;	
string $currSelection;

for ($currSelection in $sSel)
	{
		if($currSelection == "myObjectShape")
		{

			int $bDv = `getAttr ($currSelection + ".dv")`;

			if($bDv)
				print("myObjectShape.dv is on\n");
			else
				print("myObjectShape.dv is off\n");
		}
		else
			warning("myObjectShape could not be found in the selection!\n");
}
else
	warning("Nothing selected...\n");

foreach($foo in $bar)
	// blah blah
else
	// blah blah