>perl -MIO::Handle -le"(  STDOUT       )->print('foo');"
foo

>perl -MIO::Handle -le"(  *STDOUT      )->print('foo');"
foo

>perl -MIO::Handle -le"(  *STDOUT{IO}  )->print('foo');"
foo

>perl -MIO::Handle -le"(  \*STDOUT     )->print('foo');"
foo

>perl -MIO::Handle -le"(  'STDOUT'     )->print('foo');"
foo