The amazing template which does nothing

[John Colvin via Digitalmars-d]

On Tuesday, 28 April 2015 at 10:24:27 UTC, Andrea Fontana wrote:
> On Tuesday, 28 April 2015 at 10:18:49 UTC, John Colvin wrote:
>> On Tuesday, 28 April 2015 at 10:18:12 UTC, John Colvin wrote:
>>> On Tuesday, 28 April 2015 at 10:07:43 UTC, Andrea Fontana 
>>> wrote:
>>>> On Tuesday, 28 April 2015 at 09:23:53 UTC, Chris wrote:
>>>>> And this has happened to me many times. The solution "Break 
>>>>> the UFCS chain and use a local temporary variable" makes me 
>>>>> angry, because by having to do so all the beauty of 
>>>>> chaining is lost.
>>>>
>>>> A very slow (i guess) workaround could be:
>>>>
>>>> "test".toUpper.only.map!(a => "This is a " ~ 
>>>> a).front.writeln;
>>>>
>>>> vs the new one:
>>>>
>>>> "test".toUpper.Identity!(a => "This is a " ~ a).writeln;
>>>
>>> Shouldn't be slow, your just giving the optimiser some work 
>>> to do*, but you're always better off with the second one.
>>>
>>> *Assuming a good optimiser. dmd won't work this out.
>>
>> s/your/you're
>
> Trying on d.godbolt.com it seems a lot of extra-code is 
> generated for the first version.
>
> Anyway I think I'm going to rename it "apply". :)
>
> "test".toUpper.apply!(a => "This is a " ~ a).writeln;
>
> It sounds better.

The d.godbolt.org compilers seem a little out of date. I have 
found problems with their codegen/optimisation that doesn't 
happen in more recent versions.

ldc 0.15.2 based on llvm 3.5.1 reduces both chains to identical 
asm.