You can't go wrong with being explicit (close), it really depends on the rest of the code :)

undef can work, provided there is only ever a single reference / copy of filehandle, but won't close if reference count goes up  my $copy = $fh; close will always close -- explicit is good (q:gimme some? a: some what? q: that over there; q: to the left; q: lefter; :)

But if you write in narrow scopes

if( open my($fh) ... ){
1
2
3
4
5
}
[download]

implicit undef can work, as can explicit undef, as can explicit close

Which is better?  print $fh $str or die $!; close $fh or die $! ? use autodie ? Whatever fits?

It's very convenient, but this isn't mentioned anywhere in the doc and I'm not sure whether this has any negative side effects.

Often the doc is a start of a reading list, not just Ctrl+F for "close" :)

IO::File -> IO::File inherits from IO::Handle and IO::Seekable -> SEE ALSO perlfunc, I/O Operators in perlop, IO::Handle, IO::Seekable, IO::Dir

IO::Handle lists the close method

the close function which you can also use is listed at perlfunc#close , #Input and output functions, close