Re: Ligatures (was: Unify the Platforms: Cairo+FreeType+Harfbuzz Everywhere (except TTY))

[Vasilij Schneidermann]

Adding ta as new signature to a font is merely an example, any font update may 
include new supported ligatures and Emacs would need to play catch-up with them 
whenever that happens. This is undesirable from the user perspective, it's 
suboptimal to tweak font settings every time there's a significant update, time 
better spent on productive work.

I do not understand why there's a need for this kind of compromise when 
everything else supporting ligatures does support them fully, no matter the 
font and its ligature list. What is the real reason for not considering 
unconditional support? Is it technical difficulties of integration into Emacs? 
Fear of performance issues? Need of a whitelist system? Please spell out why 
you insist on enumerating every possible ligature and dismiss alternative 
approaches. I hope there to be a compelling reason for Emacs to not being  a 
first-class citizen when it comes to font support.

For the record, Sans Bullsh*t Sans and Scunthorpe Sans are two examples of 
creative use of ligatures, where entire words are replaced with a censorship 
glyph. These would not work with the proposed system, unless a full dictionary 
is added to the composition list. Which is an absurd thing to do, don't you 
agree?

Vasilij