Error: 'z' must be a number literal

[mitchgrout]

I'm creating a sequence of piano keys using the following code fragment:

  private property<[{ offset: float, note: Note }]> note-configs: [
    { offset: 0.0, note: { octave: octave, base: BaseNote.c, accidental: Accidental.neutral } },
    { offset: 0.5, note: { octave: octave, base: BaseNote.c, accidental: Accidental.sharp   } },
    { offset: 1.0, note: { octave: octave, base: BaseNote.d, accidental: Accidental.neutral } },
    { offset: 1.5, note: { octave: octave, base: BaseNote.d, accidental: Accidental.sharp   } },
    { offset: 2.0, note: { octave: octave, base: BaseNote.e, accidental: Accidental.neutral } },
    { offset: 3.0, note: { octave: octave, base: BaseNote.f, accidental: Accidental.neutral } },
    { offset: 3.5, note: { octave: octave, base: BaseNote.f, accidental: Accidental.sharp   } },
    { offset: 4.0, note: { octave: octave, base: BaseNote.g, accidental: Accidental.neutral } },
    { offset: 4.5, note: { octave: octave, base: BaseNote.g, accidental: Accidental.sharp   } },
    { offset: 5.0, note: { octave: octave, base: BaseNote.a, accidental: Accidental.neutral } },
    { offset: 5.5, note: { octave: octave, base: BaseNote.a, accidental: Accidental.sharp   } },
    { offset: 6.0, note: { octave: octave, base: BaseNote.b, accidental: Accidental.neutral } },
  ];

  for cfg in note-configs: PianoKey {
    width:  parent.width / 7;
    height: (self.note.accidental == Accidental.sharp)? (parent.height / 2) : parent.height;
    x:      cfg.offset * self.width;
    y:      0;
    note:   cfg.note;
    z:      (self.note.accidental == Accidental.neutral)? 0 : 1;
  }

I've set up my note-configs in the left-to-right order of occurrence on a keyboard, however this creation order will lead to my black notes being obscured by the white note immediately adjacent to the right of it. My thought here was to manually set the z-level of black keys to ensure they are placed on top of the neighbouring white keys, but this leads to the error:

Error: 'z' must be an number literal

What's the rationale for requiring a literal value? Is there a way I can resolve this without re-ordering my model?

[mitchgrout]

I suppose one option would be to split my model into the white/black keys, although in this case I would like to write something like...

private property<...> note-configs = { ... };
private property<...> white-note-configs = filter(note-configs, lambda-to-select-white-keys);
private property<...> black-note-configs = filter(note-configs, lambda-to-select-black-keys);

...as this would allow me to keep my config in one place, since the need to separate the configs is driven by my need to create them in a special order.

[tronical]

Yes, I'd also use a central config. Writing filter like that is not possible in .slint code yet, but using a FilterModel in Rust or C++ should be possible. You could have a callback that has basically the signature of filter as you prototyped it above and instead of lambda-to-select-white-keys you pass in the parameters you need to select the white or black keys.

Error: 'z' must be an number literal

What's the rationale for requiring a literal value? Is there a way I can resolve this without re-ordering my model?

Dynamic z ordering it not implemented yet - tracking this in #221 .