Re: Why is get(dict,value,default) evaluated eagerly?

On Thu, May 21, 2020 at 6:05 PM Lifepillar <lifepillar@lifepillar.me> wrote:
>
> I have always believed that, in get(X,y,z), z would be evaluated only
> when dictionary X does not contain key y. Today, to my surprise, I have
> discovered that it is not the case:
>
> fun! Loop()
> call Loop()
> endf
>
> let H = { 'a': 1 }
>
> if has_key(H, 'a') || Loop() " Fine, this is evaluated lazily
> endif
>
> echo (get(H, 'a') != 0) ? "" : Loop() " Fine, lazy
>
> " But, endless recursion here:
> echo get(H, 'a', Loop())
>
> What is the rationale for this behaviour?
>
> Thanks,
> Life.

IIUC, any expression in the arguments of a function (other than a
variable of type List, Dictionary, Funcref or Blob) is passed "by
value" after having been evaluated by the caller. In get(H, a, Loop())
the third argument passed is the _value_ of Loop() as evaluated
immediately before the call.

Best regards,
Tony.

--
--
You received this message from the "vim_use" maillist.
Do not top-post! Type your reply below the text you are replying to.
For more information, visit http://www.vim.org/maillist.php

---
You received this message because you are subscribed to the Google Groups "vim_use" group.
To unsubscribe from this group and stop receiving emails from it, send an email to vim_use+unsubscribe@googlegroups.com.
To view this discussion on the web visit https://groups.google.com/d/msgid/vim_use/CAJkCKXvw8NBTSQY3%3D_D4%3DY5HN%2BS5PqD9UKdr_D%2B%3DhtZW184uxg%40mail.gmail.com.