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.

Thanks for the explanation. I get it now :)
This version of Perl is default installation on a Linux 2.6 machine in my office. We do use 5.10 though for all work purpose.
And I didn't have a computer back in 1997 :)

print is a bit special, since it expects a file handle as an optional first argument, which can be a bareword.

You can eliminate that speciality by adding an explicit STDOUT:

$ perl -le 'print STDOUT one, two, three'
onetwothree
[download]

So you can have as many barewords in term position as you like.

If you leave out a comma, you have indirect method call syntax instead:

$ perl -le 'print STDOUT one, two three'
Can't locate object method "two" via package "three" (perhaps you forg
+ot to load "three"?) at -e line 1.
[download]

Okay!! Thanks!!

$ perl -MO=Deparse -e 'print cat dog'
print 'dog'->cat;
-e syntax OK
$ perl -MO=Deparse -e 'print reverse cat dog'
print reverse('dog'->cat);
-e syntax OK
[download]

I'm going to ASSUME that 5.004 has this ability, but considering it's decades old, maybe not.