Re: `new Foo` vs `new Foo()`

Yes, in hindsight, it's not particularly *useful* to consider instantiation
as a side-effect in Scala... ;)

Cheers,
Jon

On 14 July 2015 at 02:05, Haoyi Li <[email protected]> wrote:

> > I didn't mean to imply allocation is side-effecting. I meant the side
> effect of the initializer in your case class would be invoked every time
> you instantiate it, whereas the effect in an object's body occur at most
> once.
>
> Oh ok. I thought you were agreeing with jon, who said instantiating a new
> instance of a class was a side effect (???)
>
> On Mon, Jul 13, 2015 at 5:02 PM, Adriaan Moors <[email protected]>
> wrote:
>
>> I didn't mean to imply allocation is side-effecting. I meant the side
>> effect of the initializer in your case class would be invoked every time
>> you instantiate it, whereas the effect in an object's body occur at most
>> once.
>>
>> On Mon, Jul 13, 2015 at 4:05 PM, Haoyi Li <[email protected]> wrote:
>>
>>> > That's the reasoning for case classes, I guess, since a
>>> side-effect-free case class should be a case object.
>>>
>>> This doesn't make sense to me. Since when was object allocation
>>> considered side effecting? When people say "avoid side effects", they
>>> usually mean you should allocate *more* objects, not less! Is
>>> CaseClass#copy just as side-effecting as mutating vars?
>>>
>>> On Mon, Jul 13, 2015 at 2:13 PM, Adriaan Moors <[email protected]>
>>> wrote:
>>>
>>>> If we apply the same rule as for methods, you should not add parens
>>>> unless your constructor is side-effecting (which is probably not a great
>>>> idea in itself).
>>>> That's the reasoning for case classes, I guess, since a
>>>> side-effect-free case class should be a case object.
>>>>
>>>> I tend to leave off the empty parens. Their presence should imply
>>>> potential side-effects.
>>>>
>>>> On Mon, Jul 13, 2015 at 1:28 PM, Jon Pretty <[email protected]>
>>>> wrote:
>>>>
>>>>> I tend to include the parentheses for a couple of reasons: firstly
>>>>> because case classes require the parens, and by association I justify that
>>>>> classes should too, and secondly because instantiating a new instance of a
>>>>> class is side-effecting, so the "method" which does that (i.e. the
>>>>> constructor) should look like a side-effecting method.
>>>>>
>>>>> Additionally, for some reason, I prefer to write `new Foo().bar`
>>>>> rather than `(new Foo).bar`. I think the reason is that I have a slight
>>>>> discomfort at starting an expression with an opening parenthesis, and I've
>>>>> taught myself to give the `new` in `new Foo().bar` higher precedence than
>>>>> the `.`, even though this is counterintuitive to other parsing rules.
>>>>>
>>>>> Jon​
>>>>>
>>>>> On 13 July 2015 at 21:20, Rex Kerr <[email protected]> wrote:
>>>>>
>>>>>> That's the convention I use.  I've seen both with and without parens
>>>>>> in e.g. the Scala library code base.
>>>>>>
>>>>>>   --Rex
>>>>>>
>>>>>> On Mon, Jul 13, 2015 at 12:06 PM, Seth Tisue <[email protected]> wrote:
>>>>>>
>>>>>>> Is there consensus on this? Not sure whether to merge.
>>>>>>>
>>>>>>> https://github.com/scala/scala.github.com/pull/344
>>>>>>>
>>>>>>> Seth
>>>>>>>
>>>>>>>  --
>>>>>>> You received this message because you are subscribed to the Google
>>>>>>> Groups "scala-language" group.
>>>>>>> To unsubscribe from this group and stop receiving emails from it,
>>>>>>> send an email to [email protected].
>>>>>>> For more options, visit https://groups.google.com/d/optout.
>>>>>>>
>>>>>>
>>>>>>  --
>>>>>> You received this message because you are subscribed to the Google
>>>>>> Groups "scala-language" group.
>>>>>> To unsubscribe from this group and stop receiving emails from it,
>>>>>> send an email to [email protected].
>>>>>> For more options, visit https://groups.google.com/d/optout.
>>>>>>
>>>>>
>>>>>
>>>>>
>>>>> --
>>>>> Jon Pretty | @propensive
>>>>>
>>>>> --
>>>>> You received this message because you are subscribed to the Google
>>>>> Groups "scala-language" group.
>>>>> To unsubscribe from this group and stop receiving emails from it, send
>>>>> an email to [email protected].
>>>>> For more options, visit https://groups.google.com/d/optout.
>>>>>
>>>>
>>>>  --
>>>> You received this message because you are subscribed to the Google
>>>> Groups "scala-language" group.
>>>> To unsubscribe from this group and stop receiving emails from it, send
>>>> an email to [email protected].
>>>> For more options, visit https://groups.google.com/d/optout.
>>>>
>>>
>>>  --
>>> You received this message because you are subscribed to the Google
>>> Groups "scala-language" group.
>>> To unsubscribe from this group and stop receiving emails from it, send
>>> an email to [email protected].
>>> For more options, visit https://groups.google.com/d/optout.
>>>
>>
>>  --
>> You received this message because you are subscribed to the Google Groups
>> "scala-language" group.
>> To unsubscribe from this group and stop receiving emails from it, send an
>> email to [email protected].
>> For more options, visit https://groups.google.com/d/optout.
>>
>
>  --
> You received this message because you are subscribed to the Google Groups
> "scala-language" group.
> To unsubscribe from this group and stop receiving emails from it, send an
> email to [email protected].
> For more options, visit https://groups.google.com/d/optout.
>



-- 
Jon Pretty | @propensive

-- 
You received this message because you are subscribed to the Google Groups "scala-language" group.
To unsubscribe from this group and stop receiving emails from it, send an email to [email protected].
For more options, visit https://groups.google.com/d/optout.