Another idiom I wish were gone from phobos/druntime

[Atila Neves via Digitalmars-d]

On Thursday, 5 February 2015 at 05:42:59 UTC, Meta wrote:
> On Thursday, 5 February 2015 at 01:33:54 UTC, Andrei 
> Alexandrescu wrote:
>> On 2/4/15 5:32 PM, deadalnix wrote:
>>> On Thursday, 5 February 2015 at 01:07:56 UTC, Andrei 
>>> Alexandrescu wrote:
>>>> Yah, I agree "in" is useful for overridable functions. In 
>>>> fact I'd say
>>>> it's useful _only_ for overridable functions.
>>>>
>>>
>>> Putting the contract in the caller is not only useful for 
>>> overridable
>>> functions.
>>>
>>> 1/ If a lib is compiled in without contract, but your code is 
>>> compiled
>>> with, you get the in contract to run when you call library 
>>> code, but not
>>> the assert within the function.
>>>
>>> 2/ The optimizer see the properties of the argument when they 
>>> get to the
>>> in contract. This information is lost in the callee, unless 
>>> inlining
>>> goes on. that means the amount of contract the optimizer can 
>>> remove
>>> statically is greater with in contract.
>>
>> Yah, I understand the potential there. Consider me grudgingly 
>> convinced :o). -- Andrei
>
> I don't know about others (besides Beatophile, who religiously 
> adheres to writing contacts), but putting contracts on 
> functions is a hassle. I never do it unless I'm feeling 
> particularly full of divine fervor. It's a lot like making all 
> variables that don't need to be changed immutable (another 
> thing which only Bearophile seems to do) or properly 
> documenting code. Strong optimization guarantees from contracts 
> would go a long way in convincing people to actually write them 
> (although I guess that's not what you want; Perhaps you changed 
> your mind). It's a chicken and egg problem.

I also make all my variables immutable unless I can't. Which is 
annoyingly and surprisingly often. Sometimes I have to downgrade 
to const (usually because of strings), sometimes I have to rather 
sadly go back to auto. I never like it when I do. I should 
probably do more contract programming.

immutable is good. immutable is your friend. AFAIC, mutable state 
is the root of all evil.

Atila