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digitalmars.D - Re: Spec#, nullables and more

reply bearophile <bearophileHUGS lycos.com> writes:
Don:


 bearophile wrote:

 ...
 http://d.puremagic.com/issues/show_bug.cgi?id=5081







 As was pointed out in a recent post, the return value of a pure function 
 is guaranteed to be unique, so could be allowed to implictly cast to 
 immutable. I'm planning a patch for that soon, to see how well it works 
 in practice.



Right, that's the bug 5081 :-) It works with strong pure. It's a simple but
very nice idea that avoids some casts.



 But I don't think that would work for non-nulls. I don't think the two 
 situations have a great deal in common.



I see, they may have different solutions too.

Bye and thank you,
bearophile
Nov 06 2010
next sibling parent Christopher Bergqvist <chris digitalpoetry.se> writes:
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Does D have anything comparable to C++ references =E0 la "void
nullCheckLessFunction(const std::string& notNullStr) {...}" or does it only
have the equivalent of "void nullCheckingRequired(const std::string*
mightByNullStr) {...}"?

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<meta http-equiv=3D"content-type" content=3D"text/html; charset=3Dutf-8">Do=
es D have anything comparable to C++ references =E0 la &quot;void nullCheck=
LessFunction(const std::string&amp; notNullStr) {...}&quot; or does it only=
 have the equivalent of &quot;void nullCheckingRequired(const std::string* =
mightByNullStr) {...}&quot;?

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Nov 06 2010
prev sibling next sibling parent "Denis Koroskin" <2korden gmail.com> writes:
On Sat, 06 Nov 2010 14:06:20 +0300, Christopher Bergqvist  =

<chris digitalpoetry.se> wrote:


 Does D have anything comparable to C++ references =C3=A0 la "void
 nullCheckLessFunction(const std::string& notNullStr) {...}" or does it=





 only
 have the equivalent of "void nullCheckingRequired(const std::string*
 mightByNullStr) {...}"?



void nullCheckLessFunction(ref const(string) notNullStr) { .. }
Nov 06 2010
prev sibling parent Christopher Bergqvist <chris digitalpoetry.se> writes:
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On Sat, Nov 6, 2010 at 12:23 PM, Denis Koroskin <2korden gmail.com> wrote:


 On Sat, 06 Nov 2010 14:06:20 +0300, Christopher Bergqvist <
 chris digitalpoetry.se> wrote:

  Does D have anything comparable to C++ references =E0 la "void

 nullCheckLessFunction(const std::string& notNullStr) {...}" or does it
 only
 have the equivalent of "void nullCheckingRequired(const std::string*
 mightByNullStr) {...}"?



 void nullCheckLessFunction(ref const(string) notNullStr) { .. }



I made two comparison snippets between D & C++.

http://ideone.com/VPzz6 (D)
http://ideone.com/HzFRB (C++)

I feel like C++ is one small step ahead of D in this respect. It's not
possible to trust that C++ references are non-null, but at least they serve
as concise documentation of the expected contents and tend to make
surrounding code perform the null-check up front before dereferencing from
pointer to C++ reference.

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<div class=3D"gmail_quote">On Sat, Nov 6, 2010 at 12:23 PM, Denis Koroskin =
<span dir=3D"ltr">&lt;<a href=3D"mailto:2korden gmail.com">2korden gmail.co=
m</a>&gt;</span> wrote:<br><blockquote class=3D"gmail_quote" style=3D"margi=
n:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex;">
<div><div></div><div class=3D"h5">On Sat, 06 Nov 2010 14:06:20 +0300, Chris=
topher Bergqvist &lt;<a href=3D"mailto:chris digitalpoetry.se" target=3D"_b=
lank">chris digitalpoetry.se</a>&gt; wrote:<br>
<br>
<blockquote class=3D"gmail_quote" style=3D"margin:0 0 0 .8ex;border-left:1p=
x #ccc solid;padding-left:1ex">
Does D have anything comparable to C++ references =E0 la &quot;void<br>
nullCheckLessFunction(const std::string&amp; notNullStr) {...}&quot; or doe=
s it only<br>
have the equivalent of &quot;void nullCheckingRequired(const std::string*<b=
r>
mightByNullStr) {...}&quot;?<br>
</blockquote>
<br></div></div>
void nullCheckLessFunction(ref const(string) notNullStr) { .. }<br>
</blockquote></div><br><div>I made two comparison snippets between D &amp; =
C++.</div><div><br></div><div><a href=3D"http://ideone.com/VPzz6">http://id=
eone.com/VPzz6</a>=A0(D)</div><div><a href=3D"http://ideone.com/HzFRB">http=
://ideone.com/HzFRB</a>=A0(C++)</div>
<div><br></div><div>I feel like C++ is one small step ahead of D in this re=
spect. It&#39;s not possible to trust that C++ references are non-null, but=
 at least they serve as concise documentation of the expected contents and =
tend to make surrounding code perform the null-check up front before derefe=
rencing from pointer to C++ reference.</div>

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Nov 06 2010