What's the particular advantage of "to_boolean(term)" over "not
is_nil(term)"? That it supports also booleans, which however could be used
directly in predicates?
Andrea
On Wed, Dec 23, 2020 at 4:32 PM Moxley Stratton <moxley.strat...@gmail.com>
wrote:
> Here are examples:
>
> def has_access? do
> at_least_logged_in? and !!get_csrf_cookie(session)
> end
>
> %{event_form | submitted: !!event_form.submitted_at}
>
> case !!(membership_ends_on || trial_ends_on || dues_exempt) do
> true -> changeset
> false -> add_error(changeset, :membership_ends_on, "is required")
> end
>
> case !!previous_value and !!new_value do
> true -> put_change(changeset, :unconfirmed_email, new_value)
> false -> changeset
> end
>
> submitted? = !!Ecto.Changeset.get_change(changeset, :submitted_at)
>
> %{rsvpd: !!participation.rsvpd}
>
> On Tue, Dec 22, 2020 at 11:48 PM José Valim <jose.va...@dashbit.co> wrote:
>
>> Can we revisit in which scenarios an explicit boolean conversion is
>> necessary?
>>
>> On Wed, Dec 23, 2020 at 1:21 AM Moxley Stratton <
>> moxley.strat...@gmail.com> wrote:
>>
>>> I would like revisit this issue.
>>>
>>> The issue was last discussed 5 years ago. Much has changed in that time.
>>> The given solution was to use a double-negative (!!) to convert a given
>>> value to a pure boolean.
>>>
>>> Here are the problems with the suggested solution:
>>> 1. I believe this solution is a hack that is not intuitive to beginners.
>>> It's rarely seen by mid and senior developers, meaning they have to pause
>>> to interpret what !! means.
>>> 2. A double negative can't be part of an Elixir pipeline.
>>> 3. The Credo package warns about double negatives: "Double boolean
>>> negation found". Linters in other languages have a similar warning. Other
>>> languages have a built-in function (JavaScript has Boolean()) to convert to
>>> boolean.
>>> 4. The alternative to double-negative is verbose: "if expr, do: true,
>>> else: false", or the less readable "expr && true || false"
>>>
>>> I would be happy to submit a PR to add Kernel.to_boolean/1.
>>>
>>> On Sunday, November 1, 2015 at 5:48:28 AM UTC-8 José Valim wrote:
>>>
>>>> Not necessarily , but the ones in Kernel are. :)
>>>>
>>>> --
>>>>
>>>>
>>>> *José Valim*
>>>> www.plataformatec.com.br
>>>> Skype: jv.ptec
>>>> Founder and Director of R&D
>>>>
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