Nulls

[Raab, Donald]

3 seems the most reasonable option to me.

Don

> -----Original Message-----
> From: lambda-libs-spec-experts-bounces at openjdk.java.net [mailto:lambda-
> libs-spec-experts-bounces at openjdk.java.net] On Behalf Of Brian Goetz
> Sent: Wednesday, September 26, 2012 4:01 PM
> To: lambda-libs-spec-experts at openjdk.java.net
> Subject: Nulls
> 
> Trying again to categorize the choices and identify pros/cons...
> 
> Seems like there are four buckets here:
> 
> 1.  Ban nulls.  This means that feeding nulls into a Stream MUST
> produce an NPE.
> 
> 2.  Ignore nulls.
> 
> 3.  Tolerate nulls.  Streams API takes no position on nulls, but may
> well pass elements to less tolerant destinations (e.g., user-provided
> lambdas, user-provided collections, Optional constructor.)  Nulls may
> cause NPEs in these cases.
> 
> 4.  Embrace nulls.  Ensure that every operation can deal with nulls in
> a well-defined manner.  (This entails, for example, either dropping the
> Optional-bearing methods or making present Optional deal with null.)
> 
> 
> I think its safe to say that for each of these, there is some subset of
> us who finds it undesirable.
> 
> Doug proposed (2) and (4).  I proposed (3).  Nearly everyone has some
> sympathy for (1) but no one really wants to be that intolerant.
> 
> 
> Attempted summary of pros/cons:
> 
> 1 PRO: Predictable, simple
> 1 CON: Might be overly harsh, interferes with when user might actually
> want to see nulls and can deal accordingly
> 
> 2 PRO: Simple
> 2 CON: size() lies, interferes with optimizations, interferes with when
> user might actually want to see nulls and can deal accordingly
> 
> 3 PRO: Minimizes distortion on API, implementation in the null-free
> case
> 3 CON: more complex reasoning about what might happen, op behavior may
> change subtly over time as implementation changes
> 
> 4 PRO: Predictable
> 4 CON: sacrifices functionality/safety for sake of a corner case
>