[XeTeX] Question about \fontspec_set_family function of fontspec

[Will Robertson]

On 2011-09-15 02:13:15 +0930, VAFA KHALIGHI 
<vafaklg at gmail.com> said:

> Here is my minimal example. What is the difference between \newfontfamily
> and \fontspec_set_family?

Sorry, I should have added more information to that section of the 
manual. Here's the new text for \fontspec_set_family:

% Defines a new NFSS family from given \meta{features} and \meta{font},
% and stores the family name in the variable \meta{family}.
% This font family can then be selected with standard \LaTeX\ commands
% \cs{fontfamily}\marg{family}\cs{selectfont}.

In other words:

  \newfontfamily \foo [features] {myfont}
  \foo

defines a new font family and selects it (cf., \sffamily), whereas the 
equivalent with internal commands is

  \fontspec_set_family:Nnn \foofamily {features} {myfont}
  \fontfamily{\foofamily}\selectfont

(cf. \fontfamily{sf}\selectfont).

Hope this helps,
Will