[cap-talk] __equalizer and such E operations

[Bill Frantz]

kpreid at mac.com (Kevin Reid) on Tuesday, February 12, 2008 wrote:

>On Feb 12, 2008, at 20:39, Jed Donnelley wrote:
>> I wonder if an example might help?  On the surface, making objects  
>> selfless appears to make more work to compare them when a pointer  
>> compare would otherwise suffice.  What's the offsetting gain?
>
>If the 'same' value has been computed multiple times (or passed over  
>a network), then it cannot have the same creation identity;  
>therefore, a structural comparison operation is useful. (Interning is  
>not feasible because of promises.)
>
>...
>
>(This is not the best of arguments; ask MarkM if you want a better  
>one. I like E's design but I don't know everything that went into it.  
>To start with, there's probably some things to be said about  
>distributed programming.)

Selfless data can be copied over the network, since copies are
indistinguishable.  Non-selfless objects must be called remotely. 
Copying can save network round trips.

Cheers - Bill

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