on Sun Jul 17 2011, Edward Diener <eldiener-AT-tropicsoft.com> wrote:
On 7/17/2011 5:53 PM, Dave Abrahams wrote:
One can build a completely lazy MPL if you say that everything has to be a metafunction: all types are wrapped in nullary metafunctions before they are used, so you don't reach in and grab the nested ::type until you are ready to get the final result of your computation. Vesa Karvonen was the first one to do this IIUC. Unfortunately my experiments have revealed that if you rely on this idiom everywhere you get horrible compile-time performance.
What is IIUC ?
"if I understand correctly"
I did not add the nullary type metafunctions for "laziness" but just as a syntactical convenience. I hope others realize that they can use them or ignore them as they see fit and if they do slow down compile times they should be ignored.
Again, I don't know what you're actually doing here or if it's the same as what I described above. However, if you *are* doing things as I described, whatever your purpose in doing so, my point is that if you do it consistently, you /get/ laziness, /and/ you get its performance implications. -- Dave Abrahams BoostPro Computing http://www.boostpro.com