st: Deciding whether to add a filename extension

[Roger Newson <roger.newson@kcl.ac.uk>]

Fellow statalisters (especially StataCorp):

I have a query about how, in general, Stata decides whether to add an 
extension to a filename provided by the user. For instance, in the built-in 
Stata command -outfile-, if the -using- filename has no extension, then the 
extension .raw is added, but this can be overridden (at least under 
Windows) by terminating the -using- filename with a period, which causes 
the -using- file created to have a name without an extension. The default 
of adding an extension is common (eg it is used by -use- and -save- which 
both add the extension .dta by default), but is not universal. For 
instance, if we use -file open- with a filename without an extension, then 
-file open- adds no extension.

What is the algorithm used by Stata to decide whether a filename already 
has an extension? And is it the same for all operating systems? I ask 
because my own program --listtex- can fail when given a filename without an 
extension, because it uses both -outfile- and -file-, and I would like to 
fix this bug in a way that doesn't create other bugs in operating 
environments other than Windows 2000 (under which I use Stata 9.1). (Thanks 
again to Herve Stolovy for informing me about this bug.)

Best wishes (and thanks in advance)

Roger


--
Roger Newson
Lecturer in Medical Statistics
Department of Public Health Sciences
Division of Asthma, Allergy and Lung Biology
King's College London

5th Floor, Capital House
42 Weston Street
London SE1 3QD
United Kingdom

Tel: 020 7848 6648 International +44 20 7848 6648
Fax: 020 7848 6620 International +44 20 7848 6620
  or 020 7848 6605 International +44 20 7848 6605
Email: roger.newson@kcl.ac.uk
Website: http://phs.kcl.ac.uk/rogernewson/

Opinions expressed are those of the author, not the institution.

*
*   For searches and help try:
*   http://www.stata.com/support/faqs/res/findit.html
*   http://www.stata.com/support/statalist/faq
*   http://www.ats.ucla.edu/stat/stata/