How does func2 know the context?

func1(func2);

As we know Perl needs to know the context to evaluate,but in the above case 开发者_JAVA技巧how does func2 know it's in scalar or list context?

If func1 does not have a prototype (or a @ prototype), it will be list context. If func1 has a prototype of $, then it will be scalar context.

Caveat: please do not use prototypes, they're evil.

Apparently. it's list.

$ perl
sub f1 { print "called f1\n" } 
sub f2 { print "called f2\n"; print wantarray ? "list": "scalar"; print "\n"; }
f1(f2);
^d
called f2
list
called f1

Why? That's another question entirely - I assume because function params are implicitly lists come what may.