[Gretl-devel] genr command line length bug

[Riccardo (Jack) Lucchetti]

On Mon, 14 Apr 2008, Sven Schreiber wrote:

> Hi,
>
> we stumbled over a nasty genr command bug recently that screwed up the 
> results and almost went unnoticed.
>
> We have a genr command line which is very long due to the 100 involved 
> variables and their originally longish names. The result series is completely 
> bogus as we now know. The command length was about 4400 bytes (more or less, 
> maybe line endings in some aux editor program were counted or not). When the 
> variables names are shortened such that the line length drops to about 2400 
> bytes, everything is ok.
>
> The max. admissible line length should have been increased in gretl 1.7.0 due 
> to the changelog, but we observed this with more recent versions. (on 
> windows; one could have been 1.7.1, the other the most recent 1.7.4 or 1.7.3 
> I think.) What's worse, there wasn't any error message.
>
> Of course I can provide a test case if needed, but just not right now :-)

In principle, this is a bug; as such, it needs to be fixed.

However, let me point out that 4400 bytes as a command line is *insane* by 
any coding standard. If the worst comes to the worst, use functions and 
lists for such things. I'm unable to imagine a real-world case when a genr 
line cannot be tidied up decently (of course, it may be my limited 
imagination).

The fix I'd propose would be: when a command line exceeds n bytes, just 
stop execution and issue an error message, possibly complete with creative
expletives. :-)


Riccardo (Jack) Lucchetti
Dipartimento di Economia
Università Politecnica delle Marche

r.lucchetti at univpm.it
http://www.econ.univpm.it/lucchetti