Right, but I'm only after the when-invalid-key is passed:
valid:
=> (contains? "abc" 1)
true
=> (contains? ["a" "b" "c"] 1)
true
invalid:
=> (contains? "abc" "a")
IllegalArgumentException contains? not supported on type: java.lang.String
clojure.lang.RT.contains (RT.java:724)
=> (contains? ["a" "b" "c"] "a")
false
On Fri, Mar 1, 2013 at 9:02 PM, Maik Schünemann
<maikschuenem...@gmail.com>wrote:
> the old contails? debate :)
> contains? is only intented for associative collections. This explains
> (somewhat) the behavior on vectors.
> They are seen as assocuative collections from indexes to values.
> I'm not exactly sure about this, but I expect
> (contains? c x) to be true if you can call (get c x). (and get a truthy
> result except if the value is defined but nil)
> To test if a sequential collection contains the value just call .contains
> or use the (some #{x} c) idiom.
>
> The name IS misleading but after you read the docs it should be clear so i
> don't think the behaviour of contains? has to be changed.
> Greetings
>
>
> On Fri, Mar 1, 2013 at 8:36 PM, AtKaaZ <atk...@gmail.com> wrote:
>
>> I don't think I understand what you mean (could you rephrase/example?), I
>> cannot think of a case when I wouldn't want it to throw when I'm passing a
>> non-number (contains? [:a :b :c] :a), I mean, rather than just silently
>> ignoring.
>> It;s not unlike this:
>> => (contains? '(:a :b :c) :a)
>>
>> IllegalArgumentException contains? not supported on type:
>> clojure.lang.PersistentList clojure.lang.RT.contains (RT.java:724)
>>
>> it throws because, it's similarly better than just ignoring it and
>> propagating the bug somewhere else.
>>
>> I don't know about others but, I would prefer if the constraints of a
>> function's definition are violated by ie. devs calling it wrongly (maybe
>> not even anticipating that it could be called wrongly due to it being like
>> generic - perhaps in a manner that you've explained and I didn't quite
>> understand) are enforced and exceptions thrown rather than silently
>> ignoring therefore allowing subtle bugs.
>>
>> In a way, it's already so for String:
>> => (contains? "aaa" 1)
>> true
>> => (contains? "aaa" 3)
>> false
>> => (contains? "aaa" "a")
>>
>> IllegalArgumentException contains? not supported on type:
>> java.lang.String clojure.lang.RT.contains (RT.java:724)
>> => (contains? "aaa" 'a)
>>
>> IllegalArgumentException contains? not supported on type:
>> java.lang.String clojure.lang.RT.contains (RT.java:724)
>>
>> Where it's almost as what I'd want for vector to be, namely: the valid
>> keys numbers, are allowed, but when invalid keys are used ie. symbol or
>> other strings, then exception is thrown; but not so for vectors; Granted
>> that the exception thrown seems to be saying something other than: bad key
>> type for passed collection (or so) but still...
>>
>> => (contains? [1 3 4] 2)
>> true
>> => (contains? [1 3 4] '2)
>> true
>> => (contains? [1 3 4] "2")
>> false
>>
>> So if you were to use this generically on any collection, you'd maybe
>> expect it to throw for vector as it does for string collection.
>>
>> Thanks for replying, Michael.
>>
>>
>> On Fri, Mar 1, 2013 at 6:03 PM, Michael Gardner <gardne...@gmail.com>wrote:
>>
>>> On Feb 28, 2013, at 17:17 , AtKaaZ <atk...@gmail.com> wrote:
>>>
>>> > According to this, can a vector have keys that are not numbers? like
>>> :a , if not, then wouldn't it make more sense that
>>> > (contains? [:a :b :c] :a) would throw ? It's probably just me.
>>>
>>> This is a reasonable point, and one I haven't seen made before. The only
>>> problem I can see with throwing an exception is that one might sometimes
>>> wish to deal with associative containers in a generic fashion, and thus end
>>> up asking a vector if it contains a keyword or a string without doing so
>>> explicitly. In that case you'd not want it to throw an exception any more
>>> than the other associative collection types would.
>>>
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>>
>>
>> --
>> Please correct me if I'm wrong or incomplete,
>> even if you think I'll subconsciously hate it.
>>
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Please correct me if I'm wrong or incomplete,
even if you think I'll subconsciously hate it.
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