I'm creating an entity-component-system architecture. To use it, you
define component types, and put a bunch of components in a map to make an
entity.
The rule for entities is that they can only have one component of any given
type, so I figured I would use the class to index it. However, since this
doesn't seem possible,
I think I'll just make my own "defcomponent" macro which acts almost like
defrecord, but makes sure that the constructor associates an appropriate
keyword type tag
in the metadata.
Looking up the metadata is slightly slower than normal type reflection, but
I doubt it will make much of a difference.
On Wednesday, 18 May 2016 11:43:22 UTC-7, Jason Felice wrote:
>
> I don't think there's a general workaround, and I'm not sure I have enough
> context to know what you are doing specifically.
>
> On Wed, May 18, 2016 at 2:28 PM, JvJ <kfjwh...@gmail.com <javascript:>>
> wrote:
>
>> I suspected as much. It would be possible to mitigate the problem by not
>> using the repl, but I want the library I'm making to be built around a
>> repl-oriented workflow (like every good clojure library should).
>>
>> Is there any way around this, or do I have to resort to :type metadata?
>>
>> On Wednesday, 18 May 2016 11:07:37 UTC-7, Jason Felice wrote:
>>>
>>> When you reload a namespace with a record, the class for that record
>>> gets recreated. It will be functionally equivalent, but a different
>>> object. I'll bet that classes hash on identity. (Though if they hashed on
>>> name, you'd still have this problem.)
>>>
>>> On Wed, May 18, 2016 at 1:31 PM, JvJ <kfjwh...@gmail.com> wrote:
>>>
>>>> I'm encountering a very strange error in some tests.
>>>>
>>>> The details are a bit complex, but I'm using type-indexed maps.
>>>>
>>>> So, given an object o, the map would be {(type o) o}. When I try to
>>>> lookup with the key (type o), I don't get the value, even though I can
>>>> clearly see it in the map.
>>>>
>>>>
>>>> I have a map instance called new-still in my tests, and I can clearly
>>>> see that this is its value
>>>>
>>>> {specs.core_test.Position {:x 0, :y 0}}
>>>>
>>>>
>>>> However, when I try to compare the first key to the Position class
>>>> (which it should be), I get this:
>>>>
>>>>
>>>> Fail in run-systems-tst
>>>> expected: (= (first (keys new-still)) Position)
>>>> actual: (not (= specs.core_test.Position specs.core_test.Position))
>>>>
>>>>
>>>>
>>>> How is it that the class specs.core_test.Position is not equal to
>>>> itself??
>>>> Is this a bug, or just some quirk of compilation?
>>>>
>>>> Thanks.
>>>>
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>>>
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