Topic: Sort of "static assert" for coverage of enumerations
Author: tomalak@gmail.com
Date: Thu, 4 Aug 2016 16:10:39 -0700 (PDT)
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Sup,
Sorry that this is so embryonic, but I wanted to open a discussion about it=
=20
before going too far down the rabbit hole. Besides, it may have been=20
considered already.
Good old fashioned enum:
enum E
{
A,
B,
C
};
Make it a scoped enum if you like.
Two ways of "ensuring" that all enumerators are considered in a switch=20
(which isn't always what you want; let's assume that, in this scenario, it=
=20
*is*):
switch (e) {
case A:
case B:
case C:
foo();
break;
=20
default:
assert(false);
}
Or my favourite =E2=80=94 omit the `default` case and pay attention to warn=
ings so=20
that you at least get immediate feedback at build time:
switch (e) {
case A:
case B:
case C:
foo();
break;
}
Maybe we should have a sort of static_assert equivalent that can break the=
=20
build when not all enumerations are covered by a switch?
Just a thought.
Discuss.....
-Lightness
--=20
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<div dir=3D"ltr">Sup,<div><br></div><div>Sorry that this is so embryonic, b=
ut I wanted to open a discussion about it before going too far down the rab=
bit hole. Besides, it may have been considered already.<div><br></div><div>=
Good old fashioned enum:</div><div><br></div><div class=3D"prettyprint" sty=
le=3D"border: 1px solid rgb(187, 187, 187); word-wrap: break-word; backgrou=
nd-color: rgb(250, 250, 250);"><code class=3D"prettyprint"><div class=3D"su=
bprettyprint"><span style=3D"color: #008;" class=3D"styled-by-prettify">enu=
m</span><span style=3D"color: #000;" class=3D"styled-by-prettify"> E<br></s=
pan><span style=3D"color: #660;" class=3D"styled-by-prettify">{</span><span=
style=3D"color: #000;" class=3D"styled-by-prettify"><br>=C2=A0 =C2=A0A</sp=
an><span style=3D"color: #660;" class=3D"styled-by-prettify">,</span><span =
style=3D"color: #000;" class=3D"styled-by-prettify"><br>=C2=A0 =C2=A0B</spa=
n><span style=3D"color: #660;" class=3D"styled-by-prettify">,</span><span s=
tyle=3D"color: #000;" class=3D"styled-by-prettify"><br>=C2=A0 =C2=A0C<br></=
span><span style=3D"color: #660;" class=3D"styled-by-prettify">};</span></d=
iv></code></div><div><br></div><div><br></div><div>Make it a scoped enum if=
you like.</div><div><br></div><div>Two ways of "ensuring" that a=
ll enumerators are considered in a switch (which isn't always what you =
want; let's assume that, in this scenario, it <i>is</i>):</div><div><br=
></div><div class=3D"prettyprint" style=3D"border: 1px solid rgb(187, 187, =
187); word-wrap: break-word; background-color: rgb(250, 250, 250);"><code c=
lass=3D"prettyprint"><div class=3D"subprettyprint"><span style=3D"color: #0=
08;" class=3D"styled-by-prettify">switch</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-b=
y-prettify">e</span><span style=3D"color: #660;" class=3D"styled-by-prettif=
y">)</span><span style=3D"color: #000;" class=3D"styled-by-prettify"> </spa=
n><span style=3D"color: #660;" class=3D"styled-by-prettify">{</span><span s=
tyle=3D"color: #000;" class=3D"styled-by-prettify"><br>=C2=A0 =C2=A0</span>=
<span style=3D"color: #008;" class=3D"styled-by-prettify">case</span><span =
style=3D"color: #000;" class=3D"styled-by-prettify"> A</span><span style=3D=
"color: #660;" class=3D"styled-by-prettify">:</span><span style=3D"color: #=
000;" class=3D"styled-by-prettify"><br>=C2=A0 =C2=A0</span><span style=3D"c=
olor: #008;" class=3D"styled-by-prettify">case</span><span style=3D"color: =
#000;" class=3D"styled-by-prettify"> B</span><span style=3D"color: #660;" c=
lass=3D"styled-by-prettify">:</span><span style=3D"color: #000;" class=3D"s=
tyled-by-prettify"><br>=C2=A0 =C2=A0</span><span style=3D"color: #008;" cla=
ss=3D"styled-by-prettify">case</span><span style=3D"color: #000;" class=3D"=
styled-by-prettify"> C</span><span style=3D"color: #660;" class=3D"styled-b=
y-prettify">:</span><span style=3D"color: #000;" class=3D"styled-by-prettif=
y"><br>=C2=A0 =C2=A0 =C2=A0 foo</span><span style=3D"color: #660;" class=3D=
"styled-by-prettify">();</span><span style=3D"color: #000;" class=3D"styled=
-by-prettify"><br>=C2=A0 =C2=A0 =C2=A0 </span><span style=3D"color: #008;" =
class=3D"styled-by-prettify">break</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 =C2=A0<br>=C2=A0 =C2=A0</span><span style=3D"colo=
r: #008;" class=3D"styled-by-prettify">default</span><span style=3D"color: =
#660;" class=3D"styled-by-prettify">:</span><span style=3D"color: #000;" cl=
ass=3D"styled-by-prettify"><br>=C2=A0 =C2=A0 =C2=A0 </span><span style=3D"c=
olor: #008;" class=3D"styled-by-prettify">assert</span><span style=3D"color=
: #660;" class=3D"styled-by-prettify">(</span><span style=3D"color: #008;" =
class=3D"styled-by-prettify">false</span><span style=3D"color: #660;" class=
=3D"styled-by-prettify">);</span><span style=3D"color: #000;" class=3D"styl=
ed-by-prettify"><br></span><span style=3D"color: #660;" class=3D"styled-by-=
prettify">}</span></div></code></div><div><br></div><div><br></div><div>Or =
my favourite =E2=80=94 omit the `default` case and pay attention to warning=
s so that you at least get immediate feedback at build time:</div><div><div=
><br></div><div class=3D"prettyprint" style=3D"border: 1px solid rgb(187, 1=
87, 187); word-wrap: break-word; background-color: rgb(250, 250, 250);"><co=
de class=3D"prettyprint"><div class=3D"subprettyprint"><span style=3D"color=
: #008;" class=3D"styled-by-prettify">switch</span><span style=3D"color: #0=
00;" class=3D"styled-by-prettify"> </span><span style=3D"color: #660;" clas=
s=3D"styled-by-prettify">(</span><span style=3D"color: #000;" class=3D"styl=
ed-by-prettify">e</span><span style=3D"color: #660;" class=3D"styled-by-pre=
ttify">)</span><span style=3D"color: #000;" class=3D"styled-by-prettify"> <=
/span><span style=3D"color: #660;" class=3D"styled-by-prettify">{</span><sp=
an style=3D"color: #000;" class=3D"styled-by-prettify"><br>=C2=A0 =C2=A0</s=
pan><span style=3D"color: #008;" class=3D"styled-by-prettify">case</span><s=
pan style=3D"color: #000;" class=3D"styled-by-prettify"> A</span><span styl=
e=3D"color: #660;" class=3D"styled-by-prettify">:</span><span style=3D"colo=
r: #000;" class=3D"styled-by-prettify"><br>=C2=A0 =C2=A0</span><span style=
=3D"color: #008;" class=3D"styled-by-prettify">case</span><span style=3D"co=
lor: #000;" class=3D"styled-by-prettify"> B</span><span style=3D"color: #66=
0;" class=3D"styled-by-prettify">:</span><span style=3D"color: #000;" class=
=3D"styled-by-prettify"><br>=C2=A0 =C2=A0</span><span style=3D"color: #008;=
" class=3D"styled-by-prettify">case</span><span style=3D"color: #000;" clas=
s=3D"styled-by-prettify"> C</span><span style=3D"color: #660;" class=3D"sty=
led-by-prettify">:</span><span style=3D"color: #000;" class=3D"styled-by-pr=
ettify"><br>=C2=A0 =C2=A0 =C2=A0foo</span><span style=3D"color: #660;" clas=
s=3D"styled-by-prettify">();</span><span style=3D"color: #000;" class=3D"st=
yled-by-prettify"><br>=C2=A0 =C2=A0 =C2=A0</span><span style=3D"color: #008=
;" class=3D"styled-by-prettify">break</span><span style=3D"color: #660;" cl=
ass=3D"styled-by-prettify">;</span><span style=3D"color: #000;" class=3D"st=
yled-by-prettify"><br></span><span style=3D"color: #660;" class=3D"styled-b=
y-prettify">}</span></div></code></div><div><br></div></div><div><br></div>=
<div>Maybe we should have a sort of static_assert=C2=A0equivalent that can =
break the build when not all enumerations are covered by a switch?</div><di=
v><br></div><div>Just a thought.</div><div><br></div><div>Discuss.....</div=
><div><br></div><div><br></div><div>-Lightness</div></div></div>
<p></p>
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