In the recent discussion of ref($class)||$class, it was proposed that the idiom somehow makes it worse when a method is accidentally called as a function. I don't quite follow this, but quickly tried a workaround:

# instead of
my $class = shift;
my $self = bless {}, ref($class) || $class;
# try
my $self = bless {}, ref($_[0]) || @_
[download]

Note that || does properly propagate list context onto its right operand. The problem is that bless has a "$;$" prototype, so there isn't list context, there's scalar context instead. So calling it as a function results in a blessing into class "0" :)

open also suffers from this (it has a "*;$@" prototype). So if you want a sub to do some processing and then turn around and open a file passing through its parameters to open, you can't do:

sub foo {
   # some stuff
   open my $fh, @_;
   return $fh;
}
[download]

Instead you need:

sub foo {
   # some stuff
   my $fh;
   if (@_ == 1) {
      open $fh, $_[0];
   } else {
      open $fh, $_[0], $_[1], @_[2..$#_];
   }
   return $fh;
}
[download]

which IMO is real ugly (TM).

What bothers me most is that I can't think of any good reason *why* the optional args should have scalar context for either bless or open. Prototypes of "$@" and "*@" would be just as good in any case I can think of. I can't help but think that someone fell prey to what I call prototypitis; that is, using prototypes to describe what a function expects, rather than using them to control how a function is called.

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