Perl version 5.004_04? Where did you get that?

• perl -e 'print cat': "cat" is treated as an unopened file-handle (a typeglob) in package 'main', and compiled as print cat $_.
• perl -e 'print cat dog': Indirect object syntax (the syntax that many wish would go away. It's Perl's equivalent of "the most vexing parse"). See perlobj#Invoking-Class-Methods. Compiles as print dog->cat;
• perl -e 'print reverse cat': 'reverse' is treated as a function, and 'cat' is treated as a simple unquoted string. Compiles as print reverse('cat'); reverse is called in list context, so you don't see much happening since there's only one argument.
• perl -e 'print reverse cat dog': There's the most vexing parse again: Compiles as print reverse dog->cat;

Perl probably has plenty of other "most vexing parses", so I shouldn't really direct that phrase at indirect object syntax in particular, but it's one easy target.

5.004_04      1997-Oct-15: Do you remember what specs your computer had in 1997? I think I had a Pentium-I with a 2GB hard drive and maybe 128MB RAM.