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=20

Hi

Idea is simple. Make instance temporally constant.
=20
Small example:
    Container<int> c;=20
    func( *const*( c ) );=20
    *const*( c ).f();
=20
=20
And in details:
 =20
=20
Table of Contents.

   - I. Abstract
   - II. Motivation
   - III. Solution
   - IV. Syntax
   - V. Summary
   - VI. Impact On the Standard
  =20
I. Abstract
Dynamic constatization of instances.=20
II. Motivation
Problem 1:[*Example*:=20

template< typename T>
 class Container{
   public:
     typedef T* iterator;
     typedef T const* const_iterator;
     iterator begin();
     const_iterator begin()const;
     iterator end();
     const_iterator end()const;
     void f();
     void f()const;
  };

  Container<int> cont;

  for( auto const & iter : cont ){ // in here we want to be called *begin()=
const* and *end()const*
  }

=E2=80=94*end example*]
=20
Problem 2:
[*Example*:=20

   void func( Container<int> & c );
   void func( Container<int> const & c );

   void do_something(){
    Container<int> cont;

    func(cont); // In here we want to call func( Container<int> const& c );
   }

=E2=80=94*end example*]=20
=20

III. Solution
Solutions within current standard=20
  =20
   - Bloat code with new functions that has different name which will serve=
=20
   to only to only one purpose.
   Examples are: vector::cbegin and vector::cend, vector::crbegin,=20
   vector::crend.=20
   - Use helper variable with const qualifier.
   =20
   [*Example*:=20
  =20
     {
      Container<int> const& ccont =3D cont;
      for( auto & iter : cont ){
      }
     }
  =20
   =E2=80=94*end example*]=20
   - Use some of existing cast operator which will directly lead to=20
   misunderstanding and possible to something more serious.=20
   [*Example*:=20
  =20
     // Some companies might forbid usage of reinterpret_cast
     for( auto const & iter : reinterpret_cast< Container<int> const& >( co=
nt ) ){
       // ... ... ...
     }
  =20
     for( auto const & iter : static_cast< Container<int> const& >( cont ) =
){
       // ... ... ...
     }
     // it is expected that const_cast remove constness not to add
     for( auto const & iter : const_cast< Container<int> const& >( cont ) )=
{
       // ... ... ...
     }
  =20
     for( auto const & iter : ( Container<int> const& )( cont ) ){
         // ... ... ...
     }
    =20
  =20
   =E2=80=94*end example*]
   =20
   In all cases code become less readable if we have type with realy long=
=20
   name e.g. std::map< std::string, std::pair< std::string, std::string > >=
..=20
  =20
  =20
By adding ability to const to act on instances.On range loop:
[*Example*:=20

Container<int> cont;
for( auto &iter : const( cont ) ){
 // ...
 }

=E2=80=94*end example*]=20
=20
On instance:
[*Example*:=20

Container<int> cont;

func( const( cont ) );

const( cont ).f();


=E2=80=94*end example*]=20
=20
On pointers:
[*Example*:=20

Container<int> cont;

Container<int> * cp1 =3D &cont;
const( cp1 )->f();
Container<int> *const cp2 =3D &cont;
const( cp2 )->f();
Container<int> const* cp3 =3D &cont;
const( cp3 )->f();

=E2=80=94*end example*]=20

IV. Syntax*const-operator:*const ( *expression* )

V. Summary

   - Avoid code bloat by adding functions which to allow explicit call of=
=20
   const functions.
   - Avoid misusing of cast operators to add temporal constness.
   - Avoid using of temporal const references.

VI. Impact On the Standard
  Core
    No effect.
    No new keywords.=20
    No new tokens.=20
    No changes to old syntax.=20
    Pure extension.=20
    Backward compatible.=20
  Library
    No effect.
  Existing code.
    No effect.

--=20

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<div dir=3D"ltr"><div class=3D"NaslovGlavni"><div>=C2=A0</div></div><div cl=
ass=3D"NaslovGlavni"><br></div><div class=3D"NaslovGlavni">Hi</div><div cla=
ss=3D"NaslovGlavni"><br></div><div class=3D"NaslovGlavni">Idea is simple. M=
ake instance temporally constant.</div><div class=3D"NaslovGlavni"><div>=C2=
=A0</div></div><div class=3D"NaslovGlavni">Small example:</div><div class=
=3D"NaslovGlavni"></div><div class=3D"NaslovGlavni"><font face=3D"courier n=
ew,monospace">=C2=A0=C2=A0=C2=A0 Container&lt;int&gt; c;=C2=A0<div>=C2=A0=
=C2=A0=C2=A0 func( <em>const</em>( c ) );=C2=A0</div><div>=C2=A0=C2=A0=C2=
=A0 <em>const</em>( c ).f();</div></font><div><font face=3D"courier new,mon=
ospace"></font>=C2=A0</div><div>=C2=A0</div><div>And in details:</div></div=
><div class=3D"NaslovGlavni"><div>=C2=A0=C2=A0</div></div><dt><div class=3D=
"NaslovGlavni"><div>=C2=A0</div></div></dt><dt><div class=3D"NaslovGlavni">=
Table of Contents.</div></dt><dd><ul><li><div class=3D"TOCItem">I. Abstract=
</div></li><li><div class=3D"TOCItem">II. Motivation</div></li><li><div cla=
ss=3D"TOCItem">III. Solution</div></li><li><div class=3D"TOCItem">IV. Synta=
x</div></li><li><div class=3D"TOCItem">V. Summary</div></li><li><div class=
=3D"TOCItem">VI. Impact On the Standard</div></li></ul></dd><dt><div class=
=3D"NaslovGlavni">I. Abstract</div></dt><dd>    Dynamic constatization of i=
nstances.    </dd><dt><div class=3D"NaslovGlavni">II. Motivation</div></dt>=
<dd><dl><dt>Problem 1:</dt><dd>[<i>Example</i>: <code><pre class=3D"TextCod=
e">template&lt; typename T&gt;
 class Container{
   public:
     typedef T* iterator;
     typedef T const* const_iterator;
     iterator begin();
     const_iterator begin()const;
     iterator end();
     const_iterator end()const;
     void f();
     void f()const;
  };

  Container&lt;int&gt; cont;

  for( auto const &amp; iter : cont ){ // in here we want to be called <i>b=
egin()const</i> and <i>end()const</i>
  }
</pre></code><font face=3D"Times New Roman">     =E2=80=94<i>end example</i=
>]<div>=C2=A0</div></font><div>Problem 2:</div></dd></dl><dl><dd>    [<i>Ex=
ample</i>: <code><pre class=3D"TextCode">   void func( Container&lt;int&gt;=
 &amp; c );
   void func( Container&lt;int&gt; const &amp; c );

   void do_something(){
    Container&lt;int&gt; cont;

    func(cont); // In here we want to call func( Container&lt;int&gt; const=
&amp; c );
   }</pre></code><font face=3D"Times New Roman">=E2=80=94<i>end example</i>=
] </font><div><font face=3D"Times New Roman"></font>=C2=A0</div></dd></dl><=
p class=3D"NovaStranica"></p></dd><dt><div class=3D"NaslovGlavni">III. Solu=
tion</div></dt><dd><dl><dt class=3D"Naslovcic">Solutions within current sta=
ndard </dt><dd><ul><li>Bloat code with new functions that has different nam=
e which will serve to only to only one purpose.<div>            Examples ar=
e: <code>vector::cbegin</code> and <code>vector::cend</code>, <code>vector:=
:crbegin</code>, <code>vector::crend</code>.         </div></li><li>Use hel=
per variable with <code>const</code> qualifier.<div>=C2=A0</div><div>[<i>Ex=
ample</i>: <code></code></div><pre class=3D"TextCode"><code>  {
   Container&lt;int&gt; const&amp; ccont =3D cont;
   for( auto &amp; iter : cont ){
   }
  }
</code></pre><font face=3D"Times New Roman">=E2=80=94<i>end example</i>]   =
      </font></li><li>        Use some of existing cast operator which will=
 directly lead to misunderstanding and possible to something more serious. =
<div>[<i>Example</i>: <code></code></div><pre class=3D"TextCode"><code>  //=
 Some companies might forbid usage of reinterpret_cast
  for( auto const &amp; iter : reinterpret_cast&lt; Container&lt;int&gt; co=
nst&amp; &gt;( cont ) ){
    // ... ... ...
  }

  for( auto const &amp; iter : static_cast&lt; Container&lt;int&gt; const&a=
mp; &gt;( cont ) ){
    // ... ... ...
  }
  // it is expected that const_cast remove constness not to add
  for( auto const &amp; iter : const_cast&lt; Container&lt;int&gt; const&am=
p; &gt;( cont ) ){
    // ... ... ...
  }

  for( auto const &amp; iter : ( Container&lt;int&gt; const&amp; )( cont ) =
){
      // ... ... ...
  }
 =20
</code></pre><font face=3D"Times New Roman"> =E2=80=94<i>end example</i>]<d=
iv>=C2=A0</div></font><div><font face=3D"Times New Roman">  In all cases co=
de become less readable if we have type with realy long name e.g. </font><c=
ode>std::map&lt; std::string, std::pair&lt; std::string, std::string &gt; &=
gt;</code><font face=3D"Times New Roman">.       </font></div></li></ul></d=
d><dt class=3D"Naslovcic">By adding ability to <code>const</code> to act on=
 instances.</dt><dd>On range loop:<div> [<i>Example</i>: </div><blockquote>=
<code><pre class=3D"TextCode">Container&lt;int&gt; cont;
for( auto &amp;iter : const( cont ) ){
 // ...
 }
</pre></code><font face=3D"Times New Roman"> </font></blockquote>=E2=80=94<=
i>end example</i>] <div>=C2=A0</div><div> On instance:</div><div> [<i>Examp=
le</i>: </div><blockquote><code><pre class=3D"TextCode">Container&lt;int&gt=
; cont;

func( const( cont ) );

const( cont ).f();

</pre></code><font face=3D"Times New Roman"> </font></blockquote>=E2=80=94<=
i>end example</i>] <div>=C2=A0</div><div> On pointers:</div><div> [<i>Examp=
le</i>: </div><blockquote><code><pre class=3D"TextCode">Container&lt;int&gt=
; cont;

Container&lt;int&gt; * cp1 =3D &amp;cont;
const( cp1 )-&gt;f();
Container&lt;int&gt; *const cp2 =3D &amp;cont;
const( cp2 )-&gt;f();
Container&lt;int&gt; const* cp3 =3D &amp;cont;
const( cp3 )-&gt;f();
</pre></code><font face=3D"Times New Roman"> </font></blockquote>=E2=80=94<=
i>end example</i>]    </dd></dl><p class=3D"NovaStranica"></p></dd><dt clas=
s=3D"NaslovGlavni">IV. Syntax</dt><dd><dl><dt><i>const-operator:</i></dt><d=
d><code>const</code> ( <i>expression</i> )</dd></dl><p class=3D"NovaStranic=
a"></p></dd><dt><div class=3D"NaslovGlavni">V. Summary</div></dt><dd><ul><l=
i>Avoid code bloat by adding functions which to allow explicit call of <cod=
e>const</code> functions.</li><li>Avoid misusing of cast operators to add t=
emporal <code>const</code>ness.</li><li>Avoid using of temporal <code>const=
</code> references.</li></ul><dl></dl></dd><dt><div class=3D"NaslovGlavni">=
VI. Impact On the Standard</div></dt><dd><dl><dt><div class=3D"NaslovPod ">=
=C2=A0 Core</div></dt><dd>=C2=A0=C2=A0=C2=A0 No effect.<div>=C2=A0=C2=A0=C2=
=A0 No new keywords. </div><div>          =C2=A0=C2=A0=C2=A0 No new tokens.=
 </div><div>          =C2=A0=C2=A0=C2=A0 No changes to old syntax. </div><d=
iv>          =C2=A0=C2=A0=C2=A0 Pure extension. </div><div>          =C2=A0=
=C2=A0=C2=A0 Backward compatible.        </div></dd><dt><div class=3D"Naslo=
vPod ">=C2=A0 Library</div></dt><dd>=C2=A0=C2=A0=C2=A0 No effect.</dd><dt><=
div class=3D"NaslovPod ">=C2=A0 Existing code.</div></dt><dd>=C2=A0=C2=A0=
=C2=A0 No effect.</dd></dl></dd></div>

<p></p>

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How is this an improvement over the C++17 library feature `as_const`
<http://en.cppreference.com/w/cpp/utility/as_const>? What can your language
feature do that this library version cannot?

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<div dir="ltr">How is this an improvement over the <a href="http://en.cppreference.com/w/cpp/utility/as_const">C++17 library feature `as_const`</a>? What can your language feature do that this library version cannot?<br></div>

<p></p>

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On Saturday, January 2, 2016 at 3:27:23 PM UTC+1, Nicol Bolas wrote:
>
> How is this an improvement over the C++17 library feature `as_const`
> <http://en.cppreference.com/w/cpp/utility/as_const>? What can your
> language feature do that this library version cannot?
>

Hmm, didn't see that.
add_const is already in C++17 standard. Whit  this I can not compete,
whatever reason/feature I found/have.

So I give up!

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<div dir=3D"ltr"><br><br>On Saturday, January 2, 2016 at 3:27:23 PM UTC+1, =
Nicol Bolas wrote:<blockquote class=3D"gmail_quote" style=3D"margin: 0px 0p=
x 0px 0.8ex; padding-left: 1ex; border-left-color: rgb(204, 204, 204); bord=
er-left-width: 1px; border-left-style: solid;"><div dir=3D"ltr">How is this=
 an improvement over the <a onmousedown=3D"this.href=3D&#39;http://www.goog=
le.com/url?q\75http%3A%2F%2Fen.cppreference.com%2Fw%2Fcpp%2Futility%2Fas_co=
nst\46sa\75D\46sntz\0751\46usg\75AFQjCNGIfwIwoE1ZL6SZluDNbj3JYOlIyg&#39;;re=
turn true;" onclick=3D"this.href=3D&#39;http://www.google.com/url?q\75http%=
3A%2F%2Fen.cppreference.com%2Fw%2Fcpp%2Futility%2Fas_const\46sa\75D\46sntz\=
0751\46usg\75AFQjCNGIfwIwoE1ZL6SZluDNbj3JYOlIyg&#39;;return true;" href=3D"=
http://en.cppreference.com/w/cpp/utility/as_const" target=3D"_blank" rel=3D=
"nofollow">C++17 library feature `as_const`</a>? What can your language fea=
ture do that this library version cannot?<br></div></blockquote><div><br></=
div><div>Hmm, didn&#39;t see that.<br><font face=3D"courier new,monospace">=
add_const</font> is already in C++17 standard. Whit=C2=A0 this I can not co=
mpete, whatever reason/feature I found/have.</div><div><br>So <span class=
=3D"hps">I give up!</span></div></div>

<p></p>

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I still give up on this, but if someone want this, I grant right to to that.

And a few thing for the record.

In my eyes it is insignificant but there are some peoples who are waiting
for opportunity to exaggerate.

Scenario C++17:

for( auto& iter: std::as_const( cont ) ){
  //.. what ever
 }
Compiler must enter in as_const to see what is inside and at the end it
will optimize as we want/expect.
But this require some time.

This proposal scenario:
 for( auto& iter: const( cont ) ){
   //.. what ever
  }
Compiler will just add 'const', No optimization of any kind.
Much faster than c++17.

And again some people are very peaky regarding even for a smallest thing.
'goto' is almost banned, I have complain on using 'continue'.

'Companies rules' ( famous experiment with monkeys ) is fact, similarly it
is time to have 'C++ ( monkey ) rules'.

etc.

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<div dir=3D"ltr"><div><br>I still give up on this, but if someone want this=
, I grant right to to that.</div><div><br></div><div>And a few thing for th=
e record.</div><div><br></div><div>In my eyes it is insignificant but there=
 are some peoples who are waiting for opportunity to exaggerate.</div><div>=
<br></div><p>Scenario C++17:</p><p><font face=3D"courier new,monospace">for=
( auto&amp; iter: std::as_const( cont ) ){<br>=C2=A0 //.. what ever<br>=C2=
=A0}</font></p><div>Compiler must enter in <font face=3D"courier new,monosp=
ace">as_const</font> to see what is inside and at the end it will optimize =
as we want/expect.<br>But this require some time.</div><div><br></div><p>Th=
is proposal scenario:<br><font face=3D"courier new,monospace">=C2=A0for( au=
to&amp; iter: const( cont ) ){<br>=C2=A0=C2=A0 //.. what ever<br>=C2=A0 }</=
font></p><div>Compiler will just add &#39;const&#39;, No optimization of an=
y kind.<br>Much faster than c++17.</div><div><br></div><p>And again some pe=
ople are very peaky regarding even for a smallest thing. <br><font face=3D"=
courier new,monospace">&#39;goto&#39;</font> is almost banned, I have compl=
ain on using <font face=3D"courier new,monospace">&#39;continue&#39;</font>=
..</p><p>&#39;Companies rules&#39; ( famous experiment with monkeys ) is fac=
t, similarly it is time to have &#39;C++ ( monkey ) rules&#39;.</p><p>etc.<=
br></p></div>

<p></p>

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