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Hi All,

One of the nice safety features of enum classes is that they cannot be
implicitly converted to their underlying type. However, do you think we
would lose this safety feature if we allowed an explicit conversion to the
underlying type?

I do not know of any practical use of explicit conversion operators except
for the contextual conversion to bool. And it is only this conversion that
I am interested in.

It would be beneficial to have a unique Boolean type that would not be
convertible to another unique Boolean type. One solution is to use an enum
class with `bool` as underlying type:

enum class SkipUnused : bool { No, Yes };
enum class SkipNeative : bool { No, Yes };

void process(SkipUnused skipUnused)
{
  if (skipUnused) // doesn't compile
    {}
}

Unfortunately, such enum-based type does not work with boolean expressions.
It would we had an explicit conversion.

Do you think, it would be acceptable to add such explicit conversion to the
underlying type, for enum classes?

Regards,
&rzej;

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<div dir=3D"ltr">Hi All,<br><br>One of the nice safety features of enum cla=
sses is that they cannot be implicitly converted to their underlying type. =
However, do you think we would lose this safety feature if we allowed an ex=
plicit conversion to the underlying type?<br><br>I do not know of any pract=
ical use of explicit conversion operators except for the contextual convers=
ion to bool. And it is only this conversion that I am interested in.<br><br=
>It would be beneficial to have a unique Boolean type that would not be con=
vertible to another unique Boolean type. One solution is to use an enum cla=
ss with `bool` as underlying type:<br><br><div style=3D"background-color: r=
gb(250, 250, 250); border-color: rgb(187, 187, 187); border-style: solid; b=
order-width: 1px; overflow-wrap: break-word;" class=3D"prettyprint"><code c=
lass=3D"prettyprint"><div class=3D"subprettyprint"><span style=3D"color: #0=
08;" class=3D"styled-by-prettify">enum</span><span style=3D"color: #000;" c=
lass=3D"styled-by-prettify"> </span><span style=3D"color: #008;" class=3D"s=
tyled-by-prettify">class</span><span style=3D"color: #000;" class=3D"styled=
-by-prettify"> </span><span style=3D"color: #606;" class=3D"styled-by-prett=
ify">SkipUnused</span><span style=3D"color: #000;" class=3D"styled-by-prett=
ify"> </span><span style=3D"color: #660;" class=3D"styled-by-prettify">:</s=
pan><span style=3D"color: #000;" class=3D"styled-by-prettify"> </span><span=
 style=3D"color: #008;" class=3D"styled-by-prettify">bool</span><span style=
=3D"color: #000;" class=3D"styled-by-prettify"> </span><span style=3D"color=
: #660;" class=3D"styled-by-prettify">{</span><span style=3D"color: #000;" =
class=3D"styled-by-prettify"> </span><span style=3D"color: #606;" class=3D"=
styled-by-prettify">No</span><span style=3D"color: #660;" class=3D"styled-b=
y-prettify">,</span><span style=3D"color: #000;" class=3D"styled-by-prettif=
y"> </span><span style=3D"color: #606;" class=3D"styled-by-prettify">Yes</s=
pan><span style=3D"color: #000;" class=3D"styled-by-prettify"> </span><span=
 style=3D"color: #660;" class=3D"styled-by-prettify">};</span><span style=
=3D"color: #000;" class=3D"styled-by-prettify"><br></span><span style=3D"co=
lor: #008;" class=3D"styled-by-prettify">enum</span><span style=3D"color: #=
000;" class=3D"styled-by-prettify"> </span><span style=3D"color: #008;" cla=
ss=3D"styled-by-prettify">class</span><span style=3D"color: #000;" class=3D=
"styled-by-prettify"> </span><span style=3D"color: #606;" class=3D"styled-b=
y-prettify">SkipNeative</span><span style=3D"color: #000;" class=3D"styled-=
by-prettify"> </span><span style=3D"color: #660;" class=3D"styled-by-pretti=
fy">:</span><span style=3D"color: #000;" class=3D"styled-by-prettify"> </sp=
an><span style=3D"color: #008;" class=3D"styled-by-prettify">bool</span><sp=
an style=3D"color: #000;" class=3D"styled-by-prettify"> </span><span style=
=3D"color: #660;" class=3D"styled-by-prettify">{</span><span style=3D"color=
: #000;" class=3D"styled-by-prettify"> </span><span style=3D"color: #606;" =
class=3D"styled-by-prettify">No</span><span style=3D"color: #660;" class=3D=
"styled-by-prettify">,</span><span style=3D"color: #000;" class=3D"styled-b=
y-prettify"> </span><span style=3D"color: #606;" class=3D"styled-by-prettif=
y">Yes</span><span style=3D"color: #000;" class=3D"styled-by-prettify"> </s=
pan><span style=3D"color: #660;" class=3D"styled-by-prettify">};</span><spa=
n style=3D"color: #000;" class=3D"styled-by-prettify"><br><br></span><span =
style=3D"color: #008;" class=3D"styled-by-prettify">void</span><span style=
=3D"color: #000;" class=3D"styled-by-prettify"> process</span><span style=
=3D"color: #660;" class=3D"styled-by-prettify">(</span><span style=3D"color=
: #606;" class=3D"styled-by-prettify">SkipUnused</span><span style=3D"color=
: #000;" class=3D"styled-by-prettify"> skipUnused</span><span style=3D"colo=
r: #660;" class=3D"styled-by-prettify">)</span><span style=3D"color: #000;"=
 class=3D"styled-by-prettify"><br></span><span style=3D"color: #660;" class=
=3D"styled-by-prettify">{</span><span style=3D"color: #000;" class=3D"style=
d-by-prettify"><br>=C2=A0 </span><span style=3D"color: #008;" class=3D"styl=
ed-by-prettify">if</span><span style=3D"color: #000;" class=3D"styled-by-pr=
ettify"> </span><span style=3D"color: #660;" class=3D"styled-by-prettify">(=
</span><span style=3D"color: #000;" class=3D"styled-by-prettify">skipUnused=
</span><span style=3D"color: #660;" class=3D"styled-by-prettify">)</span><s=
pan style=3D"color: #000;" class=3D"styled-by-prettify"> </span><span style=
=3D"color: #800;" class=3D"styled-by-prettify">// doesn&#39;t compile</span=
><span style=3D"color: #000;" class=3D"styled-by-prettify"><br>=C2=A0 =C2=
=A0 </span><span style=3D"color: #660;" class=3D"styled-by-prettify">{}</sp=
an><span style=3D"color: #000;" class=3D"styled-by-prettify"><br></span><sp=
an style=3D"color: #660;" class=3D"styled-by-prettify">}</span></div></code=
></div><br>Unfortunately, such enum-based type does not work with boolean e=
xpressions. It would we had an explicit conversion.<br><br>Do you think, it=
 would be acceptable to add such explicit conversion to the underlying type=
, for enum classes?<br><br>Regards,<br>&amp;rzej;<br></div>

<p></p>

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40isocpp.org?utm_medium=3Demail&utm_source=3Dfooter">https://groups.google.=
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%40isocpp.org</a>.<br />

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