I'm definitely not the right person to respond (I'm not a native speaker either), but I understand the difference like this: clutter means putting one's garbage to somewhere it doesn't belong and thus making it hard to find the real stuff (like writing temporary files into the same directory as the data files and forgeting to delete them). On the other hand to clobber is to overwrite someone elses data.

So in the first case the data are still there, but are hard(er) to find, while in the second they are gone.

Getting back to Perl ... if you export all your symbols to the main namespace you are cluttering it and if you overwrite someone elses variable you are clobbering.

Jenda
Always code as if the guy who ends up maintaining your code will be a violent psychopath who knows where you live.
   -- Rick Osborne

Edit by castaway: Closed small tag in signature

"clobber" is commonly used to mean "overwrite". This has been true for over a decade (csh has had a "noclobber" option for more than 10 years).

Now "clobber a predefined variable" can be made more precise as "clobber a predefined variable's value". In the original(?) use of the term, it was a file that was being overwritten, which makes the distinction even less problematic since the clobbering of the file's contents was often accomplished by overwriting the file with a different file (now with the same name that the original file used to have) rather than by keeping the same file and just overwriting the contents of that file (but both were possible and the distinction was rarely important since the point was that your file's original data was no longer available via the original file name).

So I find it natural to interpret "clobber a predefined variable" as "clobber a predefined variable's value" in the absence of any evidence that we are actually talking about the less-common act of removing variables from symbol tables or replacing them.

"Clutter" certainly doesn't fit this case, as Jenda explains.