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Date: Wed, 24 Apr 2013 09:08:19 +0100
From: lipska the kat <"nospam at neversurrender dot co dot uk">
Organization: Trollbusters 3
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Subject: Re: <? extends String>
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On 23/04/13 20:26, Daniel Pitts wrote:
> On 4/23/13 11:33 AM, lipska the kat wrote:
>> On 23/04/13 17:58, Daniel Pitts wrote:
>>> On 4/23/13 9:30 AM, lipska the kat wrote:
>>>> On 23/04/13 16:50, Daniel Pitts wrote:
>>>>> On 4/23/13 8:37 AM, lipska the kat wrote:
>>>>>> On 23/04/13 14:55, Steven Simpson wrote:
>>>>>>> On 23/04/13 11:31, Donkey Hottie wrote:
>>>>>>>> 23.04.2013 12:48, Steven Simpson kirjoitti:
>>>>>>>>> public static String generateWindowsArgument(List<? extends
>>>>>>>>> String>
>>>>>>>>> args) {
>>>>>>>> <offtopic>java.lang.String is final, so nothing can extend it.
>>>>>>>> </offtopic>

[snip]

>> Actually, in a way, List<? extends String> as a parameter to a method
>> might be considered as breaking encapsulation ... you are actually
>> exposing part of the internal workings of a component.
>
> What about the internal workings? That it accepts a List of things it
> can treat as Strings. I'm not seeing how that's breaking any encapsulation.

No, it is a bit of a leap I agree, allow me to elucidate.

Using List<? extends <final class>> as a parameter exposes the fact that 
the internal workings do not modify the list ... think about it, what 
additional information does it convey about the internal workings of the 
method ...

Tenuous maybe but no more tenuous that justifying the use of
List<? extends String> by saying that String may be made mutable in future.

You know what, this sort of thing makes me really quite angry. Years of 
looking at other peoples crappy code has left me with a pathological 
aversion to this type of pointless academic fluff. What is more worrying 
is that there is a good chance that this sort of nonsense is being 
propagated down the academic chain to tomorrows graduates. More 
pointless crappy code to analyze, what fun.

> You're actually providing a guarantee that you won't be adding stuff to
> this List (since it is a compiler error to do so).

Huh ... it is only a compiler error within the scope of the method so 
that point is irrelevant as far as a client is concerned.
If you want to inform clients that the list is not modified do it in the 
right place, in the documentation, not by some obscure twiddling with 
the syntax that relies on the user of the method understanding the 
obscurity.

lipska

-- 
Lipska the KatŠ: Troll hunter, sandbox destroyer
and farscape dreamer of Aeryn Sun