Why can I designate a monstrous "dig" with one "Enter-move cursor-enter", but have to build walls and floors with this totally different resize-and-place technique that gives a maximum of 9x9 tiles (or 1x9 in case of walls) per build?
10x10, isn't it? (ICBW) and you can do the (2+)xN for walls, too, I'm sure, except that they'll never get built.
I think the biggest difference is that the construction interface has to lead to a materials menu, and thus has basic material accessibility checks (though see below for how to designate some 'advanced' building options). Digging/channelling etc doesn't have any restrictions. Save that I don't think so-far undiscovered cavern 'trees' can be designated for cutting prior to cavern discovery, ditto stone-smoothing (or maybe they can be, but I've never tried to check that), even though you can designate countless stairwell, channel, and mining jobs.
While I don't think it's impossible to unify the interfaces, it'd probably take some work taking two separately implemented sets of designation code and getting their common elements together to the satisfaction of any common interface instructions. While I'm sure I remember that not too long ago it wasn't even possible to designate more than a single construction at a time, I don't think there's been the opportunity to get it all compatible, with all the rest of the development going on. (Those who know better, feel free to correct me.)
If it comes to changing the dig interface, BTW, I'd at the very least like to have a way of setting up long diagonals without the same time-consuming ways (e.g.,enter-enter-KP[7|9|1|3], repeatedly), and maybe even a way of setting up a "brush" shape. If that could be applied to buildings as well, it could also save time.
(e.g.
# #####
#+++++
#+++++#
#++X++#
#+++++#
+++++#
###+# #
, which would define a not atypical building pattern of mine in a tower structure, the corner-adjacent gaps being left for the corner access building, to be filled in later, and could be applied
en-mass like applying a kennels or other workshop.
(Actually, I suspect this option is a a subset of the to-be-developed idea that buildings are no longer the exact same "place a template", but will be rooms into which the necessary items (anvil, woodturning table, dye barrel, whatever) are independently installed and used to designate the workshop area much as with tables for dining rooms. If that happens, we're probably going to want to be given a "brush template" store at the same time to let us get rooms set up how we want. Which may or may not include digging and wall/floor building designation alongside, if the whole lot gets unified.)
Anyway, on with the "how to set things to be built that you can't yet get to" tutorial, that I promised (even though it's not actually that relevant to this discussion, I realised after I typed it all in!), which I hope makes sense.
1) Set up an 'impossible to build' block of walls (also sanity checks that you have enough building materials)
#######
#######
#######
#######
#######
#######
#######
+<-already extant access point from which you will be building.
2) De-designate most walls, including some you want to keep but need to 'get past'
# #####
#
# #
# #
# #
#
# #
+
3) Infill with more floors than necessary
# #####
#+++++
#+++++#
#+++++#
#+++++#
+++++#
#+++++#
+
4) Remove the unnecessary floors, plus one
# #####
#+++++
#+++++#
#+++++#
#+++++#
+++++#
# #
+
5) Replace the walls, plus one
# #####
#+++++
#+++++#
#+++++#
#+++++#
+++++#
#######
+
6,7) Dedesignate and re-designate the wall that's your final bit of floor
# #####
#+++++
#+++++#
#+++++#
#+++++#
+++++#
###+###
+
Note that this isn't all as necessary when you're building on walls already extant on the level below, and then I'd maybe be more micromanaging start off with the corners (that the builders can diagonally shuffle around), then the floor area, then fill in all the sides. And if I was including a stairwell, that'd mean a small change. Also, if I'm building over nothing, the for-the-corner wall gaps would need to be infilled with temporary floors (or bridges, if you don't want to lose the material) to give the access you need and only removed once the corners are supported as well. You get the idea. Also, even with all that preparation I'd probably later come along and de-designate and re-designate certain cells just to pop them to the front of the construction stack, not really saving myself work, but at least making sure my plans are down pat
and finished in some vaguely rational semblance of order.