Extends seems to be defeated by superclassing. ie:
(extends? my-protocol (class {})) => false
because my-protocol is extended to IPersistentMap and (class {}) isn't
IPersistentMap it's PersistentArrayMap (which implements IPersistentMap but
extends? doesn't care)
On Thu Jan 22 2015 at 5:28:30 PM Timothy Baldridge <tbaldri...@gmail.com>
wrote:
> The logic of extends? is much simpler, so try that. IIRC it's something
> like "extends? returns true if any method on the protocol is implemented by
> x", "satisfies? returns true if all methods of a protocol are implemented
> by x".
>
> The docs don't seem to give much help here, so play with it in the repl a
> bit.
>
> Timothy
>
> On Thu, Jan 22, 2015 at 6:14 PM, Michael Blume <blume.m...@gmail.com>
> wrote:
>
>> (defprotocol my-protocol
>> (foo [this]))
>>
>> (extend-protocol my-protocol
>> clojure.lang.IPersistentMap
>> (foo [this] "hello from map"))
>>
>> (criterium.core/quick-bench
>> (satisfies? my-protocol {}))
>>
>> (criterium.core/quick-bench
>> (foo {}))
>>
>> Simply calling foo on an empty map takes 7 ns,
>> but checking whether the map satisfies my-protocol takes 22 µs, 3000
>> times longer.
>>
>> It seems like to call foo, some mechanism has to look up an
>> implementation of my-protocol for maps -- how is it we can do that so
>> quickly for a call and so slowly for satisfies?
>>
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>
>
>
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