On Saturday, March 18, 2017 17:18:15 H. S. Teoh via Digitalmars-d-learn wrote: > On Fri, Mar 17, 2017 at 02:52:39PM -0700, Ali Çehreli via Digitalmars-d- learn wrote: > > On 03/17/2017 12:05 PM, H. S. Teoh via Digitalmars-d-learn wrote: > > > 1) Template expansion / AST manipulation, and: > > > > > > 2) CTFE (compile-time function evaluation). > > > > > > Not clearly understanding the distinction between the two often > > > leads to confusion and frustration at why the compiler isn't doing > > > "what I want". > > > > I always find your posts very informative and very well articulated. > > Where is the book already? :) Or blog posts? > > [...] > > Haha, I don't think I'm up for writing a book... and I don't really keep > a blog either. But perhaps a writeup on wiki.dlang.org is in order. > > This particular topic, I think, is something somebody *should* write > about, because it seems to trip up newbies quite often. Maybe sometimes > even seasoned D users get tripped up, too (though they tend to know > better where the problem is and how to work around it). And this isn't > the first time I wrote about it. I guess it's time to consolidate what > I've written into a wiki article.
For the most part, I understand compile-time vs runtime quite well - in particular, I don't find templates vs CTFE to be all that complicated once you get into it. I find it to usually be straightforward and obvious, but there are corner cases where it gets harder to understand, and in particular, foreach with compile-time constructs gets weird enough that - to me at least - it stops being straightforward. So, to a great extent, with foreach and compile-time constructs, my understanding is primarily limited to what I need to work in order to do the stuff that I do. And I'm obviously not a D newbie. For newbies, the whole thing is going to be far harder to understand, and for whatever reason, the fact that a function run with CTFE can't use the template parameters beyond what can be done at runtime throws off a lot of people. - Jonathan M Davis
