Output Handler Return Values
The return value of the output handler is internally coerced into a string
following standard PHP type semantics, with two exceptions:
arrays and booleans.
Arrays are converted into the string "Array"
but the Array to string conversion
warning
is not triggered.
If the handler returns false
the contents of the buffer are returned.
If the handler returns true
an empty string is returned.
Note:
If a handler returns false
or throws an exception
its PHP_OUTPUT_HANDLER_DISABLED
status flag is set.