#make string into file handle

my $sBuf='';
open(my $fhOut, '>', \$sBuf); #\$sBuf is a reference to $sBuf

# make it your output stream for format/write
select $fhOut;

my ($sName, $iAge);

format SomeFormat =
Test: @<<<<<<<<<<<< @>>>>>
$sName, int($iAge)
.

$sName = "MickeyMouse";
$iAge = 82;   #born Nov, 1928
$~ = 'SomeFormat';
write;

print "buffer is: <$sBuf>\n";