I agree with you that an IllegalArgumentException is preferable
to AssertionError.
The reason that I used AssertionError was that I wanted to keep the same
behaviour as when using s/valid? (it throws an AssertionError).
Maybe only s/assert should throw AssertionError and s/valid? should throw
something else?
/Joakim
On Friday, September 16, 2016 at 7:52:55 AM UTC+2, Mamun wrote:
>
>
> When function is throwing exception because of argument. I would prefer to
> throw IllegalArgumentException not AssertionError.
>
>
> (defn check [type data]
> (if (sp/valid? type data)
> true
> (throw (IllegalArgumentException. (sp/explain type data)))))
>
>
> Br,
> Mamun
>
>
> On Friday, September 16, 2016 at 7:20:53 AM UTC+2, joakim.t...@nova.com
> wrote:
>>
>> I came up with this solution:
>>
>> (ns spec-test.core
>> (:require [clojure.spec :as s]))
>>
>> (s/def :user/name string?)
>> (s/def :common/user (s/keys :req [:user/name]))
>>
>> ;; with this little helper function...
>> (defn check [type data]
>> (if (s/valid? type data)
>> true
>> (throw (AssertionError. (s/explain type data)))))
>>
>> ;; I can use it in my :pre condition
>> (defn aname [user]
>> {:pre [(check :common/user user)]}
>> (-> user :user/name))
>>
>> ;; when I call name with an illegal arguement...
>> (aname {:x "Elon"})
>>
>> ;; ...it not fails and returns a better error message:
>> CompilerException java.lang.AssertionError: null,
>> compiling:(/Users/joakimtengstrand/IdeaProjects/spec-test/src/spec_test/core.clj:19:1)
>> val: {:x "Elon"} fails spec: :common/user predicate: (contains? % :user/name)
>>
>>
>> With this solution I don't need to enable assertions, and the code is
>> neat and less verbose!
>>
>> /Joakim
>>
>> On Thursday, September 15, 2016 at 3:11:32 PM UTC+2, Shantanu Kumar wrote:
>>>
>>> Hi Joakim,
>>>
>>> You might be interested in Paul Stadig's library
>>> https://github.com/pjstadig/assertions that leverages Java's `-ea`
>>> (enable-assertions, which you may want to keep enabled in dev) command-line
>>> flag. If you have a bunch of things together to assert, you may want to use
>>> the `when-assert` macro for wholesale optimization:
>>> https://github.com/pjstadig/assertions/blob/0.2.0/src/pjstadig/assertions.clj#L13
>>>
>>>
>>> Shantanu
>>>
>>> On Thursday, 15 September 2016 16:50:17 UTC+5:30, joakim.t...@nova.com
>>> wrote:
>>>>
>>>> Ok, thanks!
>>>>
>>>> In the Java world, the assertions is also something that need to be
>>>> turn on explicitly.
>>>> In that sence, they are kind of not mandatory to be executed (or at
>>>> least signals that to the reader of the code).
>>>>
>>>> I would be happier if you guys could add another method, that I can use
>>>> in my :pre conditions, that leverage
>>>> the same amount of details in the error messages, but that is always
>>>> "turned on".
>>>>
>>>> In the meanwhile, I will use s/assert ;-)
>>>>
>>>> BR,
>>>> Joakim Tengstrand
>>>>
>>>>
>>>> On Wednesday, 14 September 2016 15:59:09 UTC+2, Alex Miller wrote:
>>>>>
>>>>> Another option that has been added since the guide was written is
>>>>> s/assert which seems closer to what you're suggesting.
>>>>>
>>>>> (defn name [user]
>>>>> {:pre [(s/assert :common/user user)]}
>>>>> (-> user :user/name))
>>>>>
>>>>> ;; need to enable assertion checking - this can also be enabled
>>>>> globally with system property clojure.spec.check-asserts
>>>>> (s/check-asserts true)
>>>>>
>>>>> (name {:user/name "Elon"})
>>>>> "Elon"
>>>>>
>>>>> (name {:x "Elon"})
>>>>> ExceptionInfo Spec assertion failed
>>>>> val: {:x "Elon"} fails predicate: (contains? % :user/name)
>>>>> :clojure.spec/failure :assertion-failed
>>>>> clojure.core/ex-info (core.clj:4725)
>>>>>
>>>>> Rather than use it in a precondition, you can also use s/assert
>>>>> directly in the code.
>>>>>
>>>>> On Wednesday, September 14, 2016 at 7:37:24 AM UTC-5,
>>>>> joakim.t...@nova.com wrote:
>>>>>>
>>>>>> (ns spec-test.core
>>>>>> (:require [clojure.spec :as s]))
>>>>>>
>>>>>> (s/def :user/name string?)
>>>>>> (s/def :common/user (s/keys :req [:user/name]))
>>>>>>
>>>>>> ; first version of name (using :pre)
>>>>>> (defn name [user]
>>>>>> {:pre [(s/valid? :common/user user)]}
>>>>>> (-> user :user/name))
>>>>>>
>>>>>> ; This statement works ok and returns "Elon":
>>>>>> (name {:user/name "Elon"})
>>>>>>
>>>>>> ; but this statement...
>>>>>> (name {:x "Elon"})
>>>>>>
>>>>>> ;...will throw:
>>>>>> CompilerException java.lang.AssertionError:
>>>>>> Assert failed: (s/valid? :common/user user)
>>>>>>
>>>>>> ; ...but then I don't get as much information
>>>>>> ; about the error as if I would have called:
>>>>>> (s/explain :common/user {:x "Elon"})
>>>>>>
>>>>>> ;...which also contains the predicate:
>>>>>> val: {:x "Elon"} fails spec: :common/user
>>>>>> predicate: (contains? % :user/name)
>>>>>>
>>>>>> ; (second version of name - more verbose)
>>>>>> ; or do I need to wite it like this:
>>>>>> (defn name [user]
>>>>>> (let [parsed (s/conform :common/user user)]
>>>>>> (if (= parsed ::s/invalid)
>>>>>> (throw (ex-info "Invalid input" (s/explain-data :common/user
>>>>>> user)))
>>>>>> (-> user :user/name))))
>>>>>>
>>>>>> ; so that:
>>>>>> (name {:x "Elon"})
>>>>>>
>>>>>> ; ...will return:
>>>>>> CompilerException clojure.lang.ExceptionInfo:
>>>>>> Invalid input #:clojure.spec{:problems}
>>>>>> ({:path [], :pred (contains? % :user/name),
>>>>>> :val {:x "Elon"}, :via [:common/user], :in []})
>>>>>>
>>>>>> ; It should be nice if I could be able to write it like this
>>>>>> ; (or similar, to get a better error message):
>>>>>> (defn name [user]
>>>>>> {:pre [(s/explain :common/user user)]}
>>>>>> (-> user :user/name))
>>>>>>
>>>>>>
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