Optional class is just a Value

Peter Levart peter.levart at gmail.com
Fri Sep 21 08:12:55 PDT 2012

On 09/21/2012 04:53 PM, Paul Benedict wrote:
> Peter,
> In regards to the java.lang wrapper types, those implementations of 
> Optional (if it were an interface) would always have a value. The 
> clear benefit is you don't have to wrap these already boxed values in 
> a superfluous Optional wrapper.

But the clear drawback would be that badly written code, not checking 
for .isPresent(), would use the value unnoticed, causing all sorts of 
trouble (have you done any Objective-C?)...

Regards, Peter

> On Fri, Sep 21, 2012 at 9:47 AM, Peter Levart <peter.levart at gmail.com 
> <mailto:peter.levart at gmail.com>> wrote:
>     On 09/19/2012 05:47 PM, Paul Benedict wrote:
>         Brian,
>         I think the Optional class could be better named. I consider
>         it a negative
>         noun -- focusing on its ability to not contain a value.
>         Really, it is
>         nothing more than a bean for a value (and the value might be
>         absent). It
>         could have greater use than lambda so maybe it could be called
>         something
>         else.
>     I think that Optional was not meant to be used in API-s as the
>     type of a method parameters or as the type of fields,  but only as
>     the return type of methods with main usage pattern of calling it's
>     methods in a chain. For that purpose, I think the name is fine.
>     And i think it is hoped that this will be the preferred use. If
>     the Optional object is constructed late enough and discarded soon
>     enough then method in-lining and escape analysis could optimize
>     it's allocation on the stack (wishful thinking)...
>         Lacking a better suggestion myself, I thought it should be
>         called "Value"
>         ... and, if you refactored into an interface, you could
>         possibly retrofit
>         the java.lang type wrappers to implement it too.
>     Huh, how would you do that?
>     What would the "not-present" Integer look like? Would it throw
>     NullPointerException when calling .intValue()? ;-)

More information about the lambda-dev mailing list