What's the purpose of the 'in' keyword ?

[loloof64]

On Sunday, 27 May 2018 at 13:04:54 UTC, rikki cattermole wrote:
> On 28/05/2018 1:02 AM, loloof64 wrote:
>> Hello everyone,
>> 
>> I've just completed the language tour, and I am starting a 
>> tutorial in order to use Gtk binding.
>> 
>> But somewhere, they use the 'in' keyword for the constructor : 
>> (https://sites.google.com/site/gtkdtutorial/#chapter2 : in 
>> section 3 for Buttons and Callbacks, main.d snippet).
>> 
>> What's the purpose of this 'in' keyword ? I could not process 
>> a good Google request to get an answer.
>> 
>> Regards
>
> https://dlang.org/spec/function.html#parameters

Thank you very much : I'm going to look at it right now.