# [OS X TeX] Strange error

Ross Moore ross at ics.mq.edu.au
Mon Nov 12 23:41:30 CET 2007

Hi Morten,

On 13/11/2007, at 9:31 AM, Morten Høgholm wrote:

> On Mon, 12 Nov 2007 23:25:15 +0100, Ross Moore wrote:
>
> Hi Ross,
>
>> Yes. It adds an extra space token here:   (from  fink.sty )
>>
>> line 73: \long\def\IfFileExists#1#2#3{%
>> line 74:   \openin\@inputcheck#1 %
>> line 75:   \ifeof\@inputcheck
>>
>> Remove the space at the 2nd-last character of line 74 and the problem
>> completely disappears, at least in a simple test with  \begin
>> {align} .
>>
>> However, I'm not sure whether or not that space serves a legitimate
>> purpose in what this package is trying to achieve --- certainly it
>> looks like it was put there deliberately.
>
> The space is supposed to be there because ends the scanning for a
> filename for \openin. If not present, \openin will expand \ifeof
> \@inputcheck to finish scanning for the filename. The LaTeX kernel
> is identical in this respect.

Sure. That's exactly what I was worried about.
I've seen macro names get caught up within the name of a file to be

>
> The bug is elsewhere as I described earlier but that message
> probably didn't get to your part of the world yet... :-)

I've seen it, and checked it.
What I don't understand is the subtle difference that using
\begingroup ... \endgroup  makes in this context.
How is it different to  { ... } ?   or  \bgroup ... \egroup  ?

Most curious.

Cheers,

Ross

> Cheers,
> --
> Morten
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Ross Moore                                         ross at maths.mq.edu.au
Mathematics Department                             office: E7A-419
Macquarie University                               tel: +61 +2 9850 8955
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