minimal evaluation

[Daniel Keep]

downs wrote:
> Qian Xu wrote:
>> Hi All,
>>
>> Is minimal evaluation always enabled in D?
>>
>> I want to write a function IsNull(), so that I can check the precondition as
>> follows:
>>
>>   if (isNull(foo) ||
>>       isNull(foo.getBar) ||
>>       isNull(foo.getBar.getBar2)
>>   {
>>     return false;
>>   }
>>   // normal code goes here
>>
>> If an argument is null, the IsNull() will return false. Internally it will
>> be logged to console as well.
>>
>> But I am not sure, if dmd-compiler generates code without minimal evaluation
>> in some cases. If minimal evaluation is not always enabled. I cannot do
>> precodition check in my way. 
>>
>> --Qian
> 
> Short-circuit evaluation is always enabled.
> 
> http://digitalmars.com/d/1.0/expression.html#OrOrExpression
> 
> "If the left operand, converted to type bool, evaluates to true, then the right operand is not evaluated."

You beat me to it, AND you found it in the spec.

?cookie downs

  -- Daniel