Well, if you store it in metadata you'll have to look it up in the metadata
which is a hashmap lookup. As a method on a class it's a method call that
returns a constant.
On Wed, May 18, 2016 at 3:12 PM, JvJ <kfjwhee...@gmail.com> wrote:
> Will it be much better than type metadata, though?
>
> On Wednesday, 18 May 2016 12:50:48 UTC-7, tbc++ wrote:
>>
>> 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 <kfjwh...@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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>>
>>
>>
>> --
>> “One of the main causes of the fall of the Roman Empire was that–lacking
>> zero–they had no way to indicate successful termination of their C
>> programs.”
>> (Robert Firth)
>>
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“One of the main causes of the fall of the Roman Empire was that–lacking
zero–they had no way to indicate successful termination of their C
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(Robert Firth)
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