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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>>
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