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Re: looping through a list, starting at 1

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Arved Sandstrom <asandstrom3minus1@eastlink.ca> wrote:
> On 11-08-10 06:39 PM, Andreas Leitgeb wrote:
>> Lew <lewbloch@gmail.com> wrote:
>>> Volker Borchert wrote:
>>>> if (l instanceof RandomAccess) {
>>> Tests on type like this are an antipattern.
>>> Like many antipatterns there are occasions when one might
>>> consider its use anyway, but it's a red flag that we're
>>> probably going about things the wrong way.
>> 
>> Are marker-interfaces (which RandomAccess is, iirc) already an
>> antipattern, or is there a different way to check for them,
>> or are marker-interfaces just one of the occasions where one
>> would just acknowledge and consciously ignore the red flag?
>> 
>> PS: I fully agree with your judgement *outside* the context
>>   of marker-interfaces, and am eager to learn *inside* that
>>   context.
>
> I don't see that marker interfaces are an anti-pattern. I believe that
> Bloch's comments with respect to marker interfaces (Item 37 in Effective
> Java) make sense: as he points out one ought to consider a marker
> interface to be a type definition.

That doesn't make sense to me...
I can trivially create a class that inherits Object and implements
RandomAccess and doesn't offer anything of the Collection-stuff.

How would I write a method (overload) that would only take an
object if it is both List and RandomAccess? (Afaik: no way, but
I might perhaps miss something.)

Lew's argument absolutely makes sense for other types:
Rather than checking for List l, whether (l instanceof ArrayList)
I'd rather make one overload for ArrayList and another one for List.
But I cannot do something like that to separate List&RandomAccess
from List.

It's not the "no-method"-ness of marker interfaces that matters here.
They are just a trick to implement what could otherwise be implemented
with a getter:  bool supportsRandomAccess(). As they don't do it with
a method but with an interface, the syntactic way to obtain that "flag"
is using instanceof.  I don't see why this would be red-flagged without
red-flagging that concept of marker-interfaces altogether.

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Re: looping through a list, starting at 1 Arne Vajhøj <arne@vajhoej.dk> - 2011-08-01 20:32 -0400
  Re: looping through a list, starting at 1 Robert Klemme <shortcutter@googlemail.com> - 2011-08-02 02:42 -0700
    Re: looping through a list, starting at 1 v_borchert@despammed.com (Volker Borchert) - 2011-08-02 19:32 +0000
      Re: looping through a list, starting at 1 Lew <lewbloch@gmail.com> - 2011-08-10 09:00 -0700
        Re: looping through a list, starting at 1 Andreas Leitgeb <avl@gamma.logic.tuwien.ac.at> - 2011-08-10 21:39 +0000
          Re: looping through a list, starting at 1 Arved Sandstrom <asandstrom3minus1@eastlink.ca> - 2011-08-10 19:10 -0300
            Re: looping through a list, starting at 1 Andreas Leitgeb <avl@gamma.logic.tuwien.ac.at> - 2011-08-10 22:50 +0000
              Re: looping through a list, starting at 1 Arved Sandstrom <asandstrom3minus1@eastlink.ca> - 2011-08-11 07:02 -0300
                Re: looping through a list, starting at 1 Andreas Leitgeb <avl@gamma.logic.tuwien.ac.at> - 2011-08-11 11:37 +0000
                Re: looping through a list, starting at 1 Lew <lewbloch@gmail.com> - 2011-08-11 07:14 -0700
                Re: looping through a list, starting at 1 Andreas Leitgeb <avl@gamma.logic.tuwien.ac.at> - 2011-08-11 16:18 +0000
                Re: looping through a list, starting at 1 Arved Sandstrom <asandstrom3minus1@eastlink.ca> - 2011-08-11 17:39 -0300
                Re: looping through a list, starting at 1 Andreas Leitgeb <avl@gamma.logic.tuwien.ac.at> - 2011-08-12 08:09 +0000
                Re: looping through a list, starting at 1 supercalifragilisticexpialadiamaticonormalizeringelimatisticantations <supercalifragilisticexpialadiamaticonormalizeringelimatisticantations@averylongandannoyingdomainname.com> - 2011-08-11 09:52 -0400
                Re: looping through a list, starting at 1 Arved Sandstrom <asandstrom3minus1@eastlink.ca> - 2011-08-11 17:26 -0300
                Re: looping through a list, starting at 1 supercalifragilisticexpialadiamaticonormalizeringelimatisticantations <supercalifragilisticexpialadiamaticonormalizeringelimatisticantations@averylongandannoyingdomainname.com> - 2011-08-11 20:11 -0400
          Re: looping through a list, starting at 1 Lew <lewbloch@gmail.com> - 2011-08-10 20:31 -0700
            Re: looping through a list, starting at 1 Andreas Leitgeb <avl@gamma.logic.tuwien.ac.at> - 2011-08-11 16:07 +0000
              Re: looping through a list, starting at 1 Lew <lewbloch@gmail.com> - 2011-08-11 09:20 -0700
                Re: looping through a list, starting at 1 Andreas Leitgeb <avl@gamma.logic.tuwien.ac.at> - 2011-08-11 18:03 +0000
                Re: looping through a list, starting at 1 Lew <lewbloch@gmail.com> - 2011-08-11 12:55 -0700
                Re: looping through a list, starting at 1 Andreas Leitgeb <avl@gamma.logic.tuwien.ac.at> - 2011-08-12 08:32 +0000
                Re: looping through a list, starting at 1 supercalifragilisticexpialadiamaticonormalizeringelimatisticantations <supercalifragilisticexpialadiamaticonormalizeringelimatisticantations@averylongandannoyingdomainname.com> - 2011-08-12 09:09 -0400
                Re: looping through a list, starting at 1 Andreas Leitgeb <avl@gamma.logic.tuwien.ac.at> - 2011-08-12 14:38 +0000
                Re: looping through a list, starting at 1 Andreas Leitgeb <avl@gamma.logic.tuwien.ac.at> - 2011-08-12 14:51 +0000

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