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From: Nicol Bolas <jmckesson@gmail.com>
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Subject: Re: optional<T>, one more value or two states
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On Thursday, January 24, 2013 8:56:08 PM UTC-8, Tony V E wrote:
>
> On Thu, Jan 24, 2013 at 7:10 PM, Dean Michael Berris <dbe...@google.com<javascript:>> 
> wrote: 
> > 
> > In my opinion: 
> > 
> > - There's a precedent in other languages for a ".get(default_value)". 
> > Why don't we have this for optional instead? 
> > 
>
> opt.get(17) doesn't look like it is using a default to me.  Typically 
> get(17) is get the 17th element or lookup with key = 17, etc. 
>
>
> > - Why are we forcing pointer semantics on optional? Maybe there's a 
> > different concept here at play. 
> > 
>
> Because much of optional's interface is similar to pointers:  you 
> access the value with *opt and opt can be NULL. 
>
> That is the essential "problem" with optional.  Sometimes it acts 
> value-ish, sometimes pointer-ish.  It is like quantum physics - 
> sometimes a particle, sometimes a wave... 
>

But it doesn't act like a pointer. Indeed, the *only* thing "pointer-ish" 
about it is that it has an `operator*`. In every other way, it acts like a 
value.

If it helps limit confusion, we could get rid of `operator*`.

-- 

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<br><br>On Thursday, January 24, 2013 8:56:08 PM UTC-8, Tony V E wrote:<blo=
ckquote class=3D"gmail_quote" style=3D"margin: 0;margin-left: 0.8ex;border-=
left: 1px #ccc solid;padding-left: 1ex;">On Thu, Jan 24, 2013 at 7:10 PM, D=
ean Michael Berris &lt;<a href=3D"javascript:" target=3D"_blank" gdf-obfusc=
ated-mailto=3D"TMEgzGYEbWYJ">dbe...@google.com</a>&gt; wrote:
<br>&gt;
<br>&gt; In my opinion:
<br>&gt;
<br>&gt; - There's a precedent in other languages for a ".get(default_value=
)".
<br>&gt; Why don't we have this for optional instead?
<br>&gt;
<br>
<br>opt.get(17) doesn't look like it is using a default to me. &nbsp;Typica=
lly
<br>get(17) is get the 17th element or lookup with key =3D 17, etc.
<br>
<br>
<br>&gt; - Why are we forcing pointer semantics on optional? Maybe there's =
a
<br>&gt; different concept here at play.
<br>&gt;
<br>
<br>Because much of optional's interface is similar to pointers: &nbsp;you
<br>access the value with *opt and opt can be NULL.
<br>
<br>That is the essential "problem" with optional. &nbsp;Sometimes it acts
<br>value-ish, sometimes pointer-ish. &nbsp;It is like quantum physics -
<br>sometimes a particle, sometimes a wave...
<br></blockquote><div><br>But it doesn't act like a pointer. Indeed, the *o=
nly* thing "pointer-ish" about it is that it has an `operator*`. In every o=
ther way, it acts like a value.</div><br>If it helps limit confusion, we co=
uld get rid of `operator*`.<br>

<p></p>

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