Perl functions don’t have parameters, their arguments are passed in an array @_. You can simulate parameters by assigning to a list, but you can also just apply the usual array operations to @_.
sub wut {
my @args = @_;
...
}
To put in another way, Perl automatically populates the special @_ variable each time you call a function. You can access it in multiple ways:
directly, by simply using @_ or individual elements within it as $_[0], $_[1], and so on
by assigning it to another array, as shown above
by assigning it to a list of scalars (or possibly a hash, or another array, or combinations thereof):
sub wut {
my ( $arg1, $arg2, $arg3, @others ) = @_;
...
}
Note that in this form you need to put the array @others at the end, because if you put it in earlier, it’ll slurp up all of the elements of @_. In other words, this won’t work:
sub wut {
my ( $arg1, @others, $arg2 ) = @_;
...
}
You can also use shift to pull values off of @_:
sub wut {
my $arg1 = shift;
my $arg2 = shift;
my @others = @_;
...
}
Note that shift will automatically work on @_ if you don’t supply it with an argument.
You can also use named arguments by using a hash or a hash reference. For example, if you called wut() like:
wut($arg1, { option1 => 'hello', option2 => 'goodbye' });
...you could then do something like:
sub wut {
my $arg1 = shift;
my $opts = shift;
my $option1 = $opts->{option1} || "default";
my $option2 = $opts->{option2} || "default2";
...
}
This would be a good way to introduce named parameters into your functions, so that you can add parameters later and you don’t have to worry about the order in which they’re passed.
