[
https://issues.apache.org/jira/browse/LANG-819?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13862772#comment-13862772
]
Matt Benson commented on LANG-819:
----------------------------------
What have I said to lead you to conclude that I misunderstand type bounds? It
almost seems (and I hope I'm wrong) that I understand them in such a
fundamental way that I cannot be easily talked into doing something that makes
_perfect_ sense in the general case, but feels totally useless in this specific
one.
Your example is all well and good _for non-{{final}} types_, but {{Set<?
extends Foo>}} is IMHO a red herring. {{EnumSet.allOf(Foo.class)}} returns
{{EnumSet<Foo>}}, _not_ {{EnumSet<? extends Foo>}}; therefore the entire
example is contrived. If for some reason you were using a {{Set}} of whatever
element type that you didn't already _know_ was {{enum}} you'd never _pass_
that {{Set}} to {{EnumUtils#generateBitVector()}} without first somehow
checking that, at which point you'd have to cast the {{Set}} anyway to call the
bit vector method.
I comprehend that you are saying the {{? extends E}} idiom makes the compiler
disallow the modification of a {{Collection}} (an {{Iterable}} can't be
modified without casting to {{Collection}} anyway) and I can make the logical
leap that _because of this_ it may be a visual shorthand for "read-only," yet I
_still_ stubbornly refuse to be bullied by this fact when you have not:
* explained your (lacking clarification, striking me as rude and condescending)
assertion that I "misunderstand type bounds"
* provided a realistic example of code that suffers because of the current
parameter specification
* explained how [this
comment|https://issues.apache.org/jira/browse/LANG-819?focusedCommentId=13452659&page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel#comment-13452659]
is germane to the discussion
Regards,
Matt
> EnumUtils.generateBitVector needs a "? extends"
> -----------------------------------------------
>
> Key: LANG-819
> URL: https://issues.apache.org/jira/browse/LANG-819
> Project: Commons Lang
> Issue Type: Bug
> Components: lang.*
> Affects Versions: 3.0.1
> Reporter: Shevek
> Priority: Minor
>
> public static <E extends Enum<E>> long generateBitVector(Class<E>
> enumClass, Iterable<E> values) {
> Should be Iterable<? extends E>.
> This is because although no subclasses of E can exist, the "? extends" is a
> common idiom for marking the collection as readonly, or not "owned" by the
> current object.
--
This message was sent by Atlassian JIRA
(v6.1.5#6160)
