I just stumbled upon another potential mistake here. When you have specs
split across namespaces. Its possible for a map spec in one namespace to
have one of its key's use a spec from another namespace. If you forget to
require that other namespace though, you won't know, and your map will
always validate.
(s/def ::spec (s/keys :req [:other/spec]))
If :other/spec is not registered, ::spec still will succeed at being
registered. And then, assuming :other/spec is defined as:
(s/def :other/spec int?)
I wouldn't matter, since:
(s/valid? ::spec {:other/spec "123"})
Will return true.
But if you register :other/spec, it would return false.
Normally, this has not been an issue for me, but now that I share my specs
more, I've got specs in different namespace using one another, and I've
already made this mistakes a few time, causing validation I thought was
there to protect me, to actually be missing.
So I made my own keys macro:
(defmacro known-keys
[& {:keys [req req-un opt opt-un gen] :as args}]
(letfn [(known-spec? [k] (boolean (s/get-spec k)))]
(doseq [e (concat req req-un opt opt-un)]
(when (not (known-spec? e))
(throw (ex-info (str e " is not a currently registered spec.")
args)))))
`(s/keys ~@(interleave (keys args) (vals args))))
Which first checks that all keys are currently registered, and if so, it
delegates back to s/keys. Otherwise it throws an exception at macro
expansion time.
I think this would also solve OPs problem, since it would throw if typos
are made also.
On Saturday, 14 October 2017 04:45:47 UTC-7, [email protected] wrote:
>
> Hi Leon,
>
> I think it would be a mistake to introduce temporal coupling to prevent
> typos. Here is an alternative that lets you identify "missing" keys specs at
> the time and place of your choosing, and then handle them as you deem
> appropriate, without imposing those decisions on other users of spec:
>
> https://gist.github.com/stuarthalloway/f4c4297d344651c99827769e1c3d34e9
>
> Regards,
> Stu
>
>
>
>
> On Tue, Oct 10, 2017 at 12:33 PM, Leon Grapenthin <[email protected]
> <javascript:>> wrote:
>
>> In terms of code loading, acyclic dependencies turned out to be a great
>> design choice in Clojure - why its benefits shouldn't apply to or be
>> justified for spec loading is totally unclear to me.
>>
>> To make my point more clear let me recap. I am simply asking for s/keys
>> to throw if provided specs aren't registered. Because my colleagues and I
>> myself made costly mistakes that would have been prevented. The most common
>> scenario is a typo like the one I have illustrated above.
>>
>> I have asked what benefits justify current behavior?
>>
>> The only justification comes from Sean saying that it helps him
>> prototyping. While I agree I also observe that this is simultaneously the
>> trapdoor leading to such silently passing specs. And why prototyping needs
>> should not be a primary concern in how s/keys behaves.
>>
>> I have tried to make a case for current behavior: It allows to say a key
>> is there, without saying anything about its value. I have pointed out (s.
>> a.) why this IMO has too little utility to justify anything.
>>
>> Regarding Clojure being a dynamic lanugage this doesn't really make a
>> difference here: There is not much dynamic going on about registration and
>> spec in general. Registration etc. is evaluated at compile time. Note that
>> s/def, s/keys etc. are all macros whose expansion is evaluated at compile
>> time.
>>
>> On Monday, October 9, 2017 at 7:20:42 PM UTC+2, Beau Fabry wrote:
>>>
>>> > The argument that existence of specs provided to s/keys can only be
>>> checked at runtime is false.
>>>
>>> > The argument that that recursive specs are impossible if existence of
>>> specs provided to s/keys was checked at compile time is also false.
>>>
>>> Could you explain to us why this is false? Clojure is a dynamic
>>> language, as such I don't see how you could define a time when all specs
>>> need to be present. How would I enter this spec at the repl if spec
>>> definition was required at s/keys invocation time?
>>>
>>
>>
>>>
>>> On Friday, October 6, 2017 at 4:32:41 PM UTC-7, Leon Grapenthin wrote:
>>>>
>>>> The argument that existence of specs provided to s/keys can only be
>>>> checked at runtime is false.
>>>>
>>>> The argument that that recursive specs are impossible if existence of
>>>> specs provided to s/keys was checked at compile time is also false.
>>>>
>>>> The usecase for libraries is not convincing: If the libraries author
>>>> states "the map has to have a key K" nobody can spec K further since that
>>>> would be a race condition among consumers (who s/defs K first?). Requiring
>>>> the libraries author to declare K as any? would at least require him to
>>>> decide and convey his intent.
>>>>
>>>> The argument that not checking a value associated with a key is
>>>> corresponding to a guding design principle of map specs being based on a
>>>> keyset is not stating enough to justify discussed behavior. The utility of
>>>> knowing that a keyset is present is close to none, which should be the
>>>> main
>>>> reasons why s/keys validates values. Again: Saying "A map that has a key
>>>> called ::foo" is pretty pointless in Clojure. If every map in every
>>>> Clojure
>>>> program I wrote had a key ::foo they would all produce the exact same
>>>> results as if they didn't and I bet yours would, too.
>>>>
>>>> Prototyping is indeed a bit more easy if one does not have to to
>>>> declare every spec used in a s/keys. However, that is particularly damning
>>>> if you forget to add that spec later or mistype its name when doing so.
>>>> Which happens, and which is why I'm unhappy with this design letting such
>>>> typical human errors pass compilation. It would also help my prototyping
>>>> needs if I could reference symbols that are not declared, but I prefer the
>>>> compiler errors before going live.
>>>>
>>>> On Saturday, October 7, 2017 at 12:01:34 AM UTC+2, Sean Corfield wrote:
>>>>>
>>>>> As one of the (apparently pretty uncommon) users who actually does
>>>>> happily define s/keys specs without correspondingly speccing the leaves
>>>>> as
>>>>> an "incrementally lock down/validate" approach, I wouldn't be too upset
>>>>> if
>>>>> I lost that ability and it started throwing an error. I mean it throws an
>>>>> error if I go to generate it anyway.
>>>>>
>>>>>
>>>>>
>>>>> **puts hand up!**
>>>>>
>>>>>
>>>>>
>>>>> I don’t want to have to write (s/def ::some-key any?) all over the
>>>>> place as I’m developing specs, just to satisfy an overly eager checker
>>>>> (in
>>>>> my mind). Worse, since the check would need to be deferred until
>>>>> validation
>>>>> time, as Beau notes, the omission of an “any?” key spec might not even
>>>>> show
>>>>> up until much further down the line.
>>>>>
>>>>>
>>>>>
>>>>> To me, this default behavior of silently not checking the _*value*_
>>>>> associated with a _*key*_ is in keeping with the design principles of
>>>>> spec which focus on maps being based on a *key set*, while offering
>>>>> functions to allow you to optionally check values.
>>>>>
>>>>>
>>>>>
>>>>> Sean Corfield -- (970) FOR-SEAN -- (904) 302-SEAN
>>>>> An Architect's View -- http://corfield.org/
>>>>>
>>>>> "If you're not annoying somebody, you're not really alive."
>>>>> -- Margaret Atwood
>>>>>
>>>>>
>>>>> ------------------------------
>>>>> *From:* [email protected] <[email protected]> on behalf
>>>>> of Beau Fabry <[email protected]>
>>>>> *Sent:* Friday, October 6, 2017 9:10:36 AM
>>>>> *To:* Clojure
>>>>> *Subject:* Re: [core.spec] Stricter map validations?
>>>>>
>>>>> A use case that comes to mind is a system/library that specifies the
>>>>> structure of some inputs/outputs, but lets users/consumers (optionally)
>>>>> specify further validation of the leaves. I suppose that would be
>>>>> possible
>>>>> with (s/def ::foo any?) but you'd have to be a bit more careful about
>>>>> load
>>>>> order. The other use case (which is mine) is I'm just lazy and only want
>>>>> to
>>>>> write out broad strokes specs sometimes without getting into the nitty
>>>>> gritty.
>>>>>
>>>>> If s/keys were to validate that the keys it's provided have specs it
>>>>> would have to do it at validation time, so you wouldn't get the error
>>>>> until
>>>>> something was actually validated against that key spec. Trying to do it
>>>>> at
>>>>> definition time would break recursive specs.
>>>>>
>>>>> As one of the (apparently pretty uncommon) users who actually does
>>>>> happily define s/keys specs without correspondingly speccing the leaves
>>>>> as
>>>>> an "incrementally lock down/validate" approach, I wouldn't be too upset
>>>>> if
>>>>> I lost that ability and it started throwing an error. I mean it throws an
>>>>> error if I go to generate it anyway.
>>>>>
>>>>> On Friday, October 6, 2017 at 8:58:38 AM UTC-7, Leon Grapenthin wrote:
>>>>>>
>>>>>> Thanks, Beau.
>>>>>>
>>>>>> I am still interested why this default behavior has been chosen. It
>>>>>> doesn't seem like a reasonable trade-off at this point.
>>>>>>
>>>>>> It enables me to say: "The map must have this key", without
>>>>>> specifying how the data mapped to it will look like.
>>>>>>
>>>>>> If I ever wanted to do that, I could as well spec that key with
>>>>>> "any?".
>>>>>>
>>>>>> What are other benefits? They must justify the expense of likely
>>>>>> runtime errors.
>>>>>>
>>>>>>
>>>>>> On Friday, October 6, 2017 at 5:34:16 PM UTC+2, Beau Fabry wrote:
>>>>>>>
>>>>>>> Leon, perhaps you could add this code to your test suite?
>>>>>>>
>>>>>>> boot.user=> (let [kws (atom #{})]
>>>>>>> #_=> (clojure.walk/postwalk (fn [x] (when
>>>>>>> (qualified-keyword? x) (swap! kws conj x)) x) (map s/form (vals
>>>>>>> (s/registry)))) (clojure.set/difference @kws (set (keys (s/registry))))
>>>>>>> #_=> )
>>>>>>> #{:clojure.spec.alpha/v :clojure.spec.alpha/k}
>>>>>>> boot.user=>
>>>>>>>
>>>>>>> On Friday, October 6, 2017 at 5:56:29 AM UTC-7, Leon Grapenthin
>>>>>>> wrote:
>>>>>>>>
>>>>>>>> Open maps/specs are fine.
>>>>>>>>
>>>>>>>> s/keys supporting unregistered specs are not.
>>>>>>>>
>>>>>>>> At least to me. I just fixed two more bugs in production that were
>>>>>>>> would not have happened.
>>>>>>>>
>>>>>>>> What are the supposed benefits of this feature?
>>>>>>>>
>>>>>>>> I can only infer "being able to require keys without their spec
>>>>>>>> being known" which is a usecase I had exactly 0.00% of the time so far.
>>>>>>>>
>>>>>>>> Anything I have missed?
>>>>>>>>
>>>>>>>> Kind regards,
>>>>>>>> Leon.
>>>>>>>>
>>>>>>>>
>>>>>>>> On Wednesday, October 4, 2017 at 7:05:29 PM UTC+2, Beau Fabry
>>>>>>>> wrote:
>>>>>>>>>
>>>>>>>>> Seems like that's the reasonable place to check it, otherwise
>>>>>>>>> you're forced into an ordering for your specs and cannot write
>>>>>>>>> recursive
>>>>>>>>> strict map specs.
>>>>>>>>>
>>>>>>>>> On Wednesday, October 4, 2017 at 8:59:59 AM UTC-7, Yuri
>>>>>>>>> Govorushchenko wrote:
>>>>>>>>>>
>>>>>>>>>> Thanks. This approach is also different from the macro because it
>>>>>>>>>> will check specs existence at the validation time, not at the s/def
>>>>>>>>>> call.
>>>>>>>>>>
>>>>>>>>>> On Wednesday, October 4, 2017 at 4:18:16 PM UTC+3, Moritz Ulrich
>>>>>>>>>> wrote:
>>>>>>>>>>>
>>>>>>>>>>> Yuri Govorushchenko <[email protected]> writes:
>>>>>>>>>>>
>>>>>>>>>>> > Thank you the pointers! So far I ended up with writing a small
>>>>>>>>>>> `map` macro
>>>>>>>>>>> > which is similar to `s/keys` but checks that keys are already
>>>>>>>>>>> in the
>>>>>>>>>>> > registry:
>>>>>>>>>>> https://gist.github.com/metametadata/5f600e20e0e9b0ce6bce146c6db429e2
>>>>>>>>>>>
>>>>>>>>>>>
>>>>>>>>>>> Note that you can simply combine a custom predicate and `s/keys`
>>>>>>>>>>> in
>>>>>>>>>>> clojure.spec to verify that all keys in a given map have a
>>>>>>>>>>> underlying
>>>>>>>>>>> spec:
>>>>>>>>>>>
>>>>>>>>>>> ```
>>>>>>>>>>> (s/def ::whatever (s/and (s/keys ...)
>>>>>>>>>>> #(every? keyword? (keys %))
>>>>>>>>>>> #(every? (comp boolean s/get-spec)
>>>>>>>>>>> (keys %)) )
>>>>>>>>>>> ```
>>>>>>>>>>>
>>>>>>>>>> --
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