Review usage of ValueOf

[lianghai]

Values of these two objects are not known statically, therefore the usage of ValueOf and the resulted types aren’t quite useful:

harfbuzzjs/src/buffer.ts

Line 70 in e55f3ce

export type BufferSerializeFormat = ValueOf<typeof BufferSerializeFormat>;

harfbuzzjs/src/font.ts

Line 79 in e55f3ce

export type MetricsTag = ValueOf<typeof MetricsTag>;

Were the values meant to be string literals like "hasc" instead of dynamically converted numbers like hb_tag("hasc")?

[khaledhosny]

These meant to be integers (since this what HarfBuzz takes eventually and I don’t want to always to the conversion). I didn’t know these needs to be known statically (in C we use macros). I think I have to replace these with the literal number values (looks uglier, but 🤷🏾).

[lianghai]

Uh, isn’t ValueOf meant to make it convenient for users to directly provide a value (instead of having to use an object property like MetricsTag.HORIZONTAL_ASCENDER)? If you define those values as literal numbers, parameters type annotated as MetricsTag won’t be able to take a directly provided hb_tag("hasc").

[khaledhosny]

If I make them strings, wouldn’t that be API breakage?

[lianghai]

Yes.

[lianghai]

Note other function signatures like:

harfbuzzjs/src/face.ts

Line 110 in 593df6d

getTableScriptTags(table: "GSUB" | "GPOS"): string[] {

[khaledhosny]

We can’t do backward-incompatible changes now. Also, HarfBuzz sometimes allows private values in these kinds of APIs (for use cases it wants to support but do not want to advertise, for whatever reason), so I’d like to keep the API open to such uses, and the current form allows this.