SPACES

\newlanguage\mylang
\def\my{\mylang}
\char\my 2

\char\mylang 2

%*
\def\ym{1}
\char\ym 2

\def\mm{1 }
\char\mm 2

\chardef\yy=1
\char\yy 2

%*
\def\xx{\chardef\zz=1}
\xx 2
\char\zz

\def\aa{\chardef\bb=1 }
\aa 2
\char\bb 3

\def\cc{\chardef\dd=1\relax}
\cc 2
\char\dd

\bye % ---------------------

\language4
\hyphenation{ab-cdef}

\language42
\hyphenation{abc-def}

\def\ff{
  \language4%
}
\ff 2
\showhyphens{abcdef} % language4

\def\gg{
  \language\mylang
}
\gg 2
\showhyphens{abcdef} % language4

\def\hh{\language4 }
\hh 2
\showhyphens{abcdef} % language42