The :as key binds the entire _original_ map.

The :or defaults apply only to the bound variables extracted from the map.

It caught me out when I first used map destructuring but I soon got used to it.


On Fri, May 3, 2013 at 12:08 PM, Ryan <[email protected]> wrote:
> Thanks Anthony for your reply but I was already aware of that. I was hoping
> for some solution which would took care of the binding if :as was provided
> and would append the key-value to the :as parameter.
>
> I probably need to do that myself....but you never know, someone else might
> have done it and has an elegant proposal :)
>
> Ryan
>
>
> On Friday, May 3, 2013 10:04:41 PM UTC+3, Anthony Rosequist wrote:
>>
>> The value of :my-key (or the default, if :my-key doesn't exist) is being
>> bound to the symbol my-key, so all you need to do is this:
>>
>>> (defn my-function [{:keys [my-key] :or {my-key 5} :as params}]
>>>   (str "my-key value is " my-key))
>>
>>
>> On Friday, May 3, 2013 1:52:46 PM UTC-5, Ryan wrote:
>>>
>>> Hello all,
>>>
>>> I have a question regarding the default values when destructuring with
>>> :keys
>>>
>>> Let's assume that we have the following function:
>>>
>>>> (defn my-function [{:keys [my-key] :or {my-key 5} :as params}]
>>>>   (str "my-key value is " (:my-key params)))
>>>
>>>
>>> A few test runs:
>>>
>>>>
>>>> user=> (my-function {:my-key 1})
>>>> "my-key value is 1"
>>>
>>>
>>> Works as expected.
>>>
>>>> user=> (my-function {:another-key "hello"})
>>>> "my-key value is "
>>>
>>>
>>> As you can see here, my-key value is nil even thought I have a default
>>> value of 5.
>>> From the above observation, it seems that :as will not fill in the
>>> missing keys with the default values if those are provided as in my case.
>>>
>>> Does anyone have a solution for this?
>>>
>>> Thank you for your time
>>>
>>> Ryan
>
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An Architect's View -- http://corfield.org/
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-- Gustave Flaubert, French realist novelist (1821-1880)

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