Or define components to have a member called (name-as-kw [this]) returning
a keyword version of the name of the type.
On Wed, May 18, 2016 at 1:31 PM, James Reeves <ja...@booleanknot.com> wrote:
> Why not use the name of the class as the key?
>
> - James
>
> On 18 May 2016 at 20:02, JvJ <kfjwhee...@gmail.com> wrote:
>
>> 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> 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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