Tue, 5 Apr 2016 10:02:11 +0100
text/plain; charset="utf-8"; format=flowed
On 05/04/2016 09:42, Joseph Wright wrote:
> I wonder about the fact that e-TeX v1 -> v2 included adding \halign
> cells to places where \protected is 'active': presumably there was a
> good reason for this though it may (since Peter B.'s death) be hard to
> pin this down.
The driving force there were the usual problems of \if... tests doing
the wrong thing at start of array cells.
For \ifmmode that's usually avoidable by doing \relax\ifmmode but harder
(and caused us a lot of anguish at the time) is inputenc/fontenc style
tests: you want, if possible, any tests to be expandable so you don't
break kerns around accented letters, but if they are expandable and at
the start of a table cell typically they expand to the wrong thing.
Making the tests in a \protected macro would avoid that problem.....
The Numerical Algorithms Group Ltd is a company registered in England and Wales with company number 1249803. The registered office is:
Wilkinson House, Jordan Hill Road, Oxford OX2 8DR, United Kingdom.
This e-mail has been scanned for all viruses by Microsoft Office 365.