Em-dashes and compilation

What’s general practice these days for double/em-dashes? The Economist uses “word–word” (no spaces); The Guardian seems to do “word – word” (spaces preceding and following)…

I use Scrivener’s preference to convert two standard dashes to an em-dash on the fly. I precede them with a space; if they’re followed by a word I insert a second space; if by a question mark, no space. Thusly –
Roger – his trousers still around his ankles – stared in astonishment. “You mean, the prime minister actually --?”

The fun starts after compilation. I don’t re-split into two standard dashes, but leave them as em-dashes. The trouble is, the dash can turn the line from whatever preceded it. Thusly –
Roger – his trousers still around his ankles – stared in astonishment. “You mean
(and this will go on until we reach the end of the line) the prime minister actually

So after compiling I have to do a search-and-replace in Word to substitute a non-breaking space in front of em-dashes…

I’m very confused as to what constitutes good practice. And I wonder if there’s anything Scrivener does or could do to prevent orphaned em-dashes after compilation…

Why don’t you put the non-breaking spaces (opt-spacebar) in Scrivener? Or do they disappear in compilation?

Aha – is that one of those funny Macintosh key combos wot I’ve never got to grips with? Thanks, though! I can’t test it right now because I’m not in a compilation-friendly situation, but it sounds like it orta do the job…

The spaces thing depends on your grammar source. Different handbooks have different answers.

For example, AP Stylebook says to have the spaces; The Chicago Manual of Style says not to.

Personally, I prefer Chicago over AP, but the most important thing is to be consistent.

The WV style guide says “y’all just do it purty and we won’t give y’all no trouble about it. But which are these ee mmm dashes an’way? I gots me Mrs Dash’s for the cook out. That does fine by me.”

Such a lovely way with words.