Are there any differences between our defined variables and normal global variables in Perl?

Question

Is the `our` modifier only used when strict pragma is active to let using global variables or is it even used for some extra features different from normal global variables when strict is off?

Accepted Answer

Yes, `our` declarations can have additional features when compared with undeclared globals. But these are largely irrelevant.

`our` creates a lexical alias to a global variable (of the same name). That is, in `package Foo`, `our $bar` and `$Foo::bar` refer to the same variable. However, the former is only available in a tight lexical scope.

As `our` has a lexical effect, the alias can also shadow lexical variables with `my`:

```
our $foo = 42; # give some value
my  $foo = -1; # same name, different value
say "my  gives $foo";
our $foo;      # reintroduce the alias; shadow lexical
say "our gives $foo";
```

If you strip the `our` declarations and run it without strict, this obviously won't give the output

```
my  gives -1
our gives 42
```

Just like `my`, `our` can take a bit extra declaration syntax, e.g. attributes:

```
use threads::shared;
our $foo :shared;
```

You can also specify a type for usage with the `fields` pragma:

```
our Foo $foo;
```

This can't be done for global variables without `our`.

Are there any differences between our defined variables and normal global variables in Perl?

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