Modern C++ Lamentations

[Walter Bright]

On 1/3/2019 11:26 AM, Timon Gehr wrote:
> On 01.01.19 07:21, Walter Bright wrote:
>> On 12/31/2018 2:28 PM, Timon Gehr wrote:
>>> Welcome to D, where 'enum' means 'const', 'const' means 'readonly', 'lazy' 
>>> means 'by name', 'assert' means 'assume' and 'real' does not mean 'real' (in 
>>> fact, I really like the 'ireal' and 'creal' keywords, pity they are being 
>>> phased out). :)
>>
>> D's "by name" are the template alias parameters.
> 
> I think alias parameters are not "by name" they are something like "by symbol". 
> ("by name" is a bit confusing of a name, the argument expression need not really 
> have a "name".)
> 
> The standard PL jargon is this:
> 
> https://en.wikipedia.org/wiki/Evaluation_strategy#Call_by_name
> https://en.wikipedia.org/wiki/Lazy_evaluation

Thanks for the info. It seems the explanations are a little slippery, and D's 
usage doesn't precisely fit.

For example, D's lazy parameters can be used to implement control structures, as 
it says lazy evaluation is for, but then seems a bit ambiguous about whether the 
lazy evaluation is done once or many times.