---
name: "strict"
section: "3pm"
platform: "linux"
package: "perl-5.004-doc"
version: "5.004.05-6"
release: "Debian 2.2 (Potato)"
platforms: ["linux"]
url: "https://new.carta.tech/strict/3pm"
---

# strict(3pm)

Perl pragma to restrict unsafe constructs

## NAME

strict - Perl pragma to restrict unsafe constructs

## SYNOPSIS

```
    use strict;
```

```
    use strict "vars";
    use strict "refs";
    use strict "subs";
```

```
    use strict;
    no strict "vars";
```

## DESCRIPTION

If no import list is supplied, all possible restrictions are assumed. (This is the safest mode to operate in, but is sometimes too strict for casual programming.)  Currently, there are three possible things to be strict about:  "subs", "vars", and "refs".\

- `strict refs`

  This generates a runtime error if you  use symbolic references (see the *perlref* manpage).

  ```
      use strict 'refs';
      $ref = \$foo;
      print $$ref;        # ok
      $ref = "foo";
      print $$ref;        # runtime error; normally ok
  ```

- `strict vars`

  This generates a compile-time error if you access a variable that wasn't declared via `use vars`, localized via `my()` or wasn't fully qualified.  Because this is to avoid variable suicide problems and subtle dynamic scoping issues, a merely *local()* variable isn't good enough.  See the `my` entry in the *perlfunc* manpage and the `local` entry in the *perlfunc* manpage.

  ```
      use strict 'vars';
      $X::foo = 1;         # ok, fully qualified
      my $foo = 10;        # ok, my() var
      local $foo = 9;      # blows up
  ```

  ```
      package Cinna;
      use vars qw/ $bar /;        # Declares $bar in current package
      $bar = 'HgS';               # ok, global declared via pragma
  ```

  The *local()* generated a compile-time error because you just touched a global name without fully qualifying it.\

- `strict subs`

  This disables the poetry optimization, generating a compile-time error if you try to use a bareword identifier that's not a subroutine, unless it appears in curly braces or on the left hand side of the "=\>" symbol.

  ```
      use strict 'subs';
      $SIG{PIPE} = Plumber;       # blows up
      $SIG{PIPE} = "Plumber";     # just fine: bareword in curlies always ok
      $SIG{PIPE} = \&Plumber;     # preferred form
  ```

See the section on *Pragmatic Modules* in the *perlmodlib* manpage.