Re: [Engine-devel] Use java.util.Collection where possible?
BWT I did some checks on the GWT RPC that we use (deRPC) and there shouldn't be any
problems using Collection interface (or any interface) in the generic api service.
----- Original Message -----
From: "Allon Mureinik" <amureini(a)redhat.com>
To: "Yair Zaslavsky" <yzaslavs(a)redhat.com>
Cc: "engine-devel" <engine-devel(a)ovirt.org>
Sent: Sunday, March 4, 2012 6:57:24 PM
Subject: Re: [Engine-devel] Use java.util.Collection where possible?
My two cents:
There are two meanings of subtyping Collection (or any other
interface, for that matter) - additional logic and specific
implementation.
I think wherever possible, we should use the interface that infers as
much logic as possible (e.g., java.util.List for ordering,
java.util.Set for uniquness, java.util.SortedSet for natural
ordering, etc.), without inferring any specific implementation
(e.g., ArrayList, HashSet, etc.).
The flipside of this notion is that it's a mistake to use an overly
specific class/interface - when your parameter type is ArrayList,
you implicitly tell the user the *order* of his objects matter, and
that it matters to your internal algorithm to be able to do get(i)
as an O(1) operation.
Bottom line, now that I'm done with CS 101:
+1, but be careful not use interfaces that are too low.
Most methods that now receive an ArrayList will still compile if you
change the parameter type to Collection, but make sure that you
don't implicitly assume some ordering, e.g.
-Allon
----- Original Message -----
> From: "Yair Zaslavsky" <yzaslavs(a)redhat.com>
> To: "engine-devel" <engine-devel(a)ovirt.org>
> Sent: Thursday, March 1, 2012 5:18:03 PM
> Subject: [Engine-devel] Use java.util.Collection where possible?
>
> Hi,
> I see that in some places in engine-core we use Java.Util.List, or
> even
> Java.Util.ArrayList as types of method arguments, while in the
> method
> code we do nothing besides iterating over the collection.
> I then found all kinds of usages like this:
>
> x.foo(new ArrayList<MyType>(myMap.values()));
>
> As you can see need to instantiate a new ArrayList in order to use
> the
> values of the map in method foo.
> Do you see any reason why not change the argument type (at method
> signature) to Collection in such places, where possible?
>
> Yair
>
> _______________________________________________
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> Engine-devel(a)ovirt.org
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