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<p style="margin: 0px 0px 1.2em !important;">Hi David,<br>
sadly I don’t know the answer to your question as I wasn’t
around when enums were added to the language ;-)</p>
<p style="margin: 0px 0px 1.2em !important;">I agree with all
Brian said. I’d also add that the failure modes we discovered
when we worked on generic enums are rather obscure, as they are
a result of <em>three</em> factors: (i) you need to have some
class Foo that is transitioning from being non-generic to being
generic and (ii) you have to have some existing utterances of
Foo nested inside some other parameterized type (e.g. <code style="font-size: 0.85em; font-family: Consolas, Inconsolata, Courier, monospace;margin: 0px 0.15em; padding: 0px 0.3em; white-space: pre-wrap; border: 1px solid rgb(234, 234, 234); background-color: rgb(248, 248, 248); border-radius: 3px; display: inline;">Box<Foo></code><foo>)
and (iii) the declaration of that second generic class has to
be sufficiently strict (e.g. <code style="font-size: 0.85em; font-family: Consolas, Inconsolata, Courier, monospace;margin: 0px 0.15em; padding: 0px 0.3em; white-space: pre-wrap; border: 1px solid rgb(234, 234, 234); background-color: rgb(248, 248, 248); border-radius: 3px; display: inline;">Box<X extends Foo<X>></code>).
If <em>all</em> these conditions are met, then you end up
with cases where utterances of <code style="font-size: 0.85em; font-family: Consolas, Inconsolata, Courier, monospace;margin: 0px 0.15em; padding: 0px 0.3em; white-space: pre-wrap; border: 1px solid rgb(234, 234, 234); background-color: rgb(248, 248, 248); border-radius: 3px; display: inline;">Box<Foo></code><foo>
were valid before generification of Foo, but invalid
afterwards. Something like this was (and still is!) pretty
hard to spot.</foo></foo></p>
<p style="margin: 0px 0px 1.2em !important;">One might argue
(given what we know now) that it would have been perhaps better
not to make the Enum class itself generic. But the static type
checking you get on stuff like <code style="font-size: 0.85em; font-family: Consolas, Inconsolata, Courier, monospace;margin: 0px 0.15em; padding: 0px 0.3em; white-space: pre-wrap; border: 1px solid rgb(234, 234, 234); background-color: rgb(248, 248, 248); border-radius: 3px; display: inline;">EnumSet.noneOf(Foo.class)</code>
is hard to pass up: if <code style="font-size: 0.85em; font-family: Consolas, Inconsolata, Courier, monospace;margin: 0px 0.15em; padding: 0px 0.3em; white-space: pre-wrap; border: 1px solid rgb(234, 234, 234); background-color: rgb(248, 248, 248); border-radius: 3px; display: inline;">Enum</code>
wasn’t a generic class, then there’d be no way to tie the type
of the class literal to the type of the returned EnumSet. So I
think the Enum generic declaration we ended up with is the
result of a forced move (type-system wise).</p>
<p style="margin: 0px 0px 1.2em !important;">Maurizio<br>
</p>
<p style="margin: 0px 0px 1.2em !important;">On 29/03/2023 19:43,
David Alayachew wrote:</p>
<p style="margin: 0px 0px 1.2em !important;"></p>
<div class="markdown-here-exclude">
<p></p>
<blockquote type="cite" cite="mid:CAA9v-_NRPzJRrAb=Ufx=hLUKqRi7SKaotAMEz1bChOHDb63HFA@mail.gmail.com">
<div dir="auto">
<div dir="auto">Hello Maurizio,</div>
<div dir="auto"><br>
</div>
<div dir="auto">I hope you don't mind me asking, but no one
else has answered my 2nd question. And since you were the
one who wrote up most of these links that I am
referencing, it's a decent shot to see if you know the
answer lol.</div>
<div dir="auto"><br>
</div>
<div dir="auto">Why were enums never given generics in the
first place? I know they came out in the same release, so
theoretically, that was the best time possible to bake
this feature in and ensure it played well from the
beginning. Why didn't they?</div>
<div dir="auto"><br>
</div>
<div dir="auto">Thank you for your help and patience!</div>
<div dir="auto">David Alayachew</div>
</div>
</blockquote>
<p></p>
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