Contextual alternates | replace one glyph from a goup of alternates

Scripting
1

Any ideas why this code won’t work in calt?

feature calt {
  sub space space' from [space.calt1 space.calt2 space.calt3];
} calt;

Alternatively, it doesn’t work using classes either:

feature calt {
      sub space space' from @spaces;
    } calt;
2

Where did you test this?

The space glyph is often handled differently and OpenType substitute do not work.

The from substitutions are not applied automatically. It is supped to allow the user to pick a different letter by some UI.

3

I had tested it in FLS5 and InDesign. Thanks for the reply, and for the clarification of from. I’ll have to think of something else!