Why return a string that the caller doesn't care about and means nothing as opposed to returning a more simple undef value?

Excuse me? this string is what the caller requests by calling the function create_snapshot_name() which was written for this very purpose. The calling line is

  my $snap_name = create_snapshot_name();
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in function take_new_snapshot() and the name of the variable in which this return value is stored also indicates that a string is expected as return value from that function.

I am simply saying that I prefer having explicit return values.

I had those discussions before, and I stick to the perl way: a subroutine returns, absent early returns, the result of the last computed expression, with or without explicit return statement. Were I to work with you having a coding policy in place which requires always stating explicit returns, I would do likewise, otherwise not.

Edit:

Well, depends. If I was to concoct a function dependent on context for its return value, I'd use explicit returns, sometimes setting $@ if something failed. But it really boils down to two possibilities for return values as a subroutine:

1. I know what I have, and this is what you get, and might honour your context.
2. take that bastard, you get what you asked for

But then, for case 1, I would have to raise an exception if I have a list and am called in scalar context. Or should I? maybe they want just the number of elements? and vice versa.