Grokking std.container and Ranges

Mike Parker aldacron at
Mon Jun 28 20:01:42 PDT 2010

I thought I understood ranges until I actually started trying to use 
them. Now I'm having difficulties with the new range-based containers. 
So I've got two issues right now, grokking ranges and understanding the 
container interfaces.

Given an SList, I want to do the following:

foreach(obj; list)

Part of my problem is I'm not entirely clear what's going on with the 
foreach. I know it's iterating a range, but is it the SList itself being 
iterated, or is it a range returned by SList.opSlice? I assume the 
latter, which at one point led me to try this (thinking of Java's 

auto r = list[];
foreach(obj; r)

Which, of course, didn't work. I see that popFront doesn't actually 
'pop' anything off of, or out of, the range as it would in a traditional 
stack or a queue. The foreach doc says about range.popFront:

move the left edge of the range right one

Meaning, it's more like a next() than the pop() I'm familiar with 
(recalibrating all those years of C and Java terminology is not easy). 
And even if it did, changes to the range do not propagate to the 
underlying container. I understand that, at least (now).

So apparently I want something like the list.stableRemove*() variants, 
which the docs say remove an item from a container without invalidating 
any ranges currently iterating the container. Great! Only, there's no 
variant that accepts a single item. SList has removeFront and removeAny, 
and ranges can be removed via linearRemove. I can insert individual 
items fine. But how do I remove them?

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