this is odd...

hal:~> cat test.pl
package foo ;
print eval('__PACKAGE__');
hal:~> perl -l test.pl
main
hal:~> perl -le 'package foo ;print eval('__PACKAGE__');'
foo
[download]

Update: d'oh! ... that's what i get for trusting someone else's test case without looking at it closely.

what makes the -e version "work" is definitely the quotes, perl is seeing it as...

package foo ;print eval(__PACKAGE__);
[download]

...in which case the __PACKAGE__ gets interpolated before the eval.