[texhax] Some puzzling TeX

[Uwe Lueck]

\"Heiko Oberdiek" <heiko.oberdiek at googlemail.com> wrote 17.02.2011 01:48:29
> On Thu, Feb 17, 2011 at 12:44:25PM +1300, Rod Harries wrote:
>> I am trying to understand why  one would write
>> \def\:{\let\@sptoken= } \: %
> It can also be done without an extra definition:
>
> \@firstofone{\let\@sptoken= } %

That is remarkable, Heiko (tested!). 
Is this your discovery, or have you seen it elsewhere? 
It could be a proposal for latex.ltx.

Likewise, the next line in latex.ltx,

    \def\:{\@xifnch} \expandafter\def\: {\futurelet\@let at token\@ifnch}

could be replaced by 

    \@firstofone{\def\@xifnch} {\futurelet\@let at token\@ifnch}

(tested!).

Cheers, 

    Uwe.