I'm thinking of a hacky way of doing it...
(def a nil)
(def b)
=> (defn x [in]
(when (not (nil? in)) (.v in)))
#'clojurewerkz.titanium.graph-test/x
=> (x b)
#'clojurewerkz.titanium.graph-test/b
=> (x a)
nil
On Mon, Apr 29, 2013 at 7:31 PM, Gary Trakhman <[email protected]>wrote:
> If you're passing the var itself, I don't see why you'd need a macro. If
> you want to check the namespace for a var matching an unquoted symbol, you
> could do that in a macro.
>
>
> On Mon, Apr 29, 2013 at 12:29 PM, AtKaaZ <[email protected]> wrote:
>
>> Seems like a good idea to have the root binding be nil. How would you
>> make it check for bound inside the function? do we need some kind of macro?
>>
>>
>> On Mon, Apr 29, 2013 at 7:23 PM, Gary Trakhman
>> <[email protected]>wrote:
>>
>>> Why not make the root binding nil? If your decorate function is
>>> supposed to handle all vars, then they have to deal with the unbound case
>>> as that's part of the contract of vars.
>>>
>>> If it's a generic thing, then maybe make a multimethod or protocol for
>>> it.
>>>
>>>
>>> On Mon, Apr 29, 2013 at 12:17 PM, AtKaaZ <[email protected]> wrote:
>>>
>>>> I'm thinking something like (def ^:dynamic *a*) where it would make
>>>> more sense that it's unbound at first
>>>>
>>>>
>>>> On Mon, Apr 29, 2013 at 7:00 PM, Jim - FooBar();
>>>> <[email protected]>wrote:
>>>>
>>>>> I 've found that whenever I get a var-unbound exception it is almost
>>>>> always my fault and my fault only...why would you do (def a) anyway?
>>>>>
>>>>> Jim
>>>>>
>>>>>
>>>>>
>>>>> On 29/04/13 16:32, AtKaaZ wrote:
>>>>>
>>>>>> How do you guys handle the cases when the var is unbound? I mean
>>>>>> specifically in the cases where you just test if the var is nil.
>>>>>>
>>>>>> => (def a)
>>>>>> #'clojurewerkz.titanium.graph-**test/a
>>>>>>
>>>>>> => a
>>>>>> #<Unbound Unbound: #'clojurewerkz.titanium.graph-**test/a>
>>>>>>
>>>>>> => (nil? a)
>>>>>> false
>>>>>>
>>>>>> => (bound? a)
>>>>>> ClassCastException clojure.lang.Var$Unbound cannot be cast to
>>>>>> clojure.lang.Var clojure.core/bound?/fn--4837 (core.clj:4954)
>>>>>>
>>>>>> => (bound? #'a)
>>>>>> false
>>>>>>
>>>>>> ok imagine the following sample :))
>>>>>>
>>>>>> => (defn decorate [input]
>>>>>> (when (not (nil? input)) (str "prefix:" input ":suffix")))
>>>>>> #'clojurewerkz.titanium.graph-**test/decorate
>>>>>>
>>>>>> => (decorate "1")
>>>>>> "prefix:1:suffix"
>>>>>>
>>>>>> => (decorate a)
>>>>>> "prefix:Unbound: #'clojurewerkz.titanium.graph-**test/a:suffix"
>>>>>>
>>>>>> so... fix?
>>>>>> but more importantly does anyone need to add checks for
>>>>>> is-the-var-bound in their code where they checked for nil ?
>>>>>>
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