Inconsistent single quote expansion inside of double quotes

[TrevorBurnham]

Inside of single quotes, double quote expansion works as you'd expect: A pair is always formed; if you select text, then double quotes are formed around it.

Now try typing

"#{foo}"

If you place the cursor at the end of the string and type ', you get one single quote:

"#{foo}'"

If you place the cursor at the start of the string and do the same, you get two:

"''#{foo}"

And if you select anything inside of the string (outside of the interpolation), the ' you type simply replaces what you've selected:

"'"

But within the interpolation, single quote expansions work as you'd expect:

"#{'foo'}"

The behaviors are identical with backticks (`) as well.

None of these behaviors is so bad in and of itself, but the inconsistency is annoying. I'm guessing that it's the result of someone overthinking a bit—what's the behavior supposed to be if a selection includes part of an interpolation when someone hits '? But that's an edge case (the selection was probably made by mistake); a much more common case is when you want to surround an interpolation with single quotes:

"You typed '#{input}'."

Right now, doing that common operation takes not one keystroke, not two, but at least three—one to put a pair of single quotes in front of the interpolation, another to delete half the pair, and another to add a single quote after it.

I think it would be a great improvement to simply expand all single quotes (and backticks) typed inside of double quotes, the way that double quotes are always expanded inside of single quotes.