Another idiom I wish were gone from phobos/druntime

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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.