Re: `add-face'

[Lars Magne Ingebrigtsen <larsi@gnus.org>]

Chong Yidong <cyd@gnu.org> writes:

>> + If NOREPLACE, add the text properties instead of replacing any
>> + existing ones.  This is mainly useful for faces.

[...]

> This is too vague.  What does "add the text properties" mean?  If the
> current value of a property is nil, and the argument to
> add-text-properties specifies a value `foo', does the new value become
> `foo' or `(foo)'?

The former, but it probably doesn't matter?

> If the current value is `1', does the new value become `(foo 1)' or
> something else?

`(foo 1)' is, I think, the only reasonable way to interpret "add".

> And, specifically for face properties, what if the current value is a
> list specifying an anonymous face, like `(:foreground "black")'?

Oh, it doesn't.  Hm.  That's a problem...  is there any reliable way to
distinguish `(:foreground "black")' from `(bold italic)'?

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