Daniel Jalkut, on OS X’s “Smart Subsitutions” (e.g., replacing `dumb` quotes like " with smart ones like “):
It’s a good thing.
However, the feature can be vexing when typing in contexts where typographic beauty is clearly not the priority. For example the behavior would not make sense in a code editor like Xcode or BBEdit. These apps are more often used to write text that will please a programming language compiler or interpreter, where a string for example must be enclosed by “straight quotes”, and “smart quotes” would only lead to a syntax error.
As Jalkut notes later, disabling substitutions system-wide is the easiest fix. But it’s also akin to using a sledgehammer to hang a small canvas on the wall. Doing so would mean apps such as Tweetbot won’t—for better or for worse—replace double/triple dashes and/or dumb quotes automatically.
So what does Jalkut suggest?
Thanks to the flexibility of Apple’s “user defaults” system for registering preferences on a system-wide and app-specific basis, you can impose override preferences for these options on the specific apps of your choosing.
And if you hate the command line:
Update: My old friend Chris DeSalvo, who also happens to work at Slack on the Mac Slack app points out that there is a much simpler solution for Slack in particular:
@danielpunkass @jsatk @SlackHQ You could also go to Edit > Substitutions within the app and disable them there.
— Chris DeSalvo (@chrisdesalvo) February 24, 2016
I just confirmed that this seems to work well
Ah, the ol’ Edit → Substitutions.
It’s disheartening to know just how many things I’ve learned over the years, only to forget them later (👴🏾?)