In your example, the round brackets around the $x don't do anything, as the right hand side of the assignment must be in scalar context.

Perhaps the reason you have that code fragment is that it is similar to one popular way of passing function arguments:

sub do_stuff {
    my($x,$y,$z) = @_;
    ...
}
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In one company I worked at, the coding convention extended the idiom to this form (with the comments on each argument.):

sub do_stuff {
    my(
      $x,   # X axis coordinate.
      $y,   # Y axis coordinate.
      $z,   # Z axis coordinate.
    ) = @_;
    ...
}
[download]