Permissions

A permission is simply a text string stored in the handler permissions on Objects and Accounts. Think of it as a specialized sort of Tag - one specifically dedicated to access checking. They are thus often tightly coupled to Locks. Permission strings are not case-sensitive, so “Builder” is the same as “builder” etc.

Permissions are used as a convenient way to structure access levels and hierarchies. It is set by the perm command and checked by the PermissionHandler.check method as well as by the specially the perm() and pperm() lock functions.

All new accounts are given a default set of permissions defined by settings.PERMISSION_ACCOUNT_DEFAULT.

Managing Permissions

In-game, you use the perm command to add and remove permissions j perm/account Tommy = Builders perm/account/del Tommy = Builders

Note the use of the /account switch. It means you assign the permission to the Accounts Tommy instead of any Character that also happens to be named “Tommy”.

There can be reasons for putting permissions on Objects (especially NPCS), but for granting powers to players, you should usually put the permission on the Account - this guarantees that they are kept, regardless of which Character they are currently puppeting. This is especially important to remember when assigning permissions from the hierarchy tree (see below), as an Account’s permissions will overrule that of its character. So to be sure to avoid confusion you should generally put hierarchy permissions on the Account, not on their Characters (but see also quelling).

In code, you add/remove Permissions via the PermissionHandler, which sits on all typeclassed entities as the property .permissions:

    account.permissions.add("Builders")
    account.permissions.add("cool_guy")
    obj.permissions.add("Blacksmith")
    obj.permissions.remove("Blacksmith")

The permission hierarchy

Selected permission strings can be organized in a permission hierarchy by editing the tuple settings.PERMISSION_HIERARCHY. Evennia’s default permission hierarchy is as follows (in increasing order of power):

 Player           # can chat and send tells (default level) (lowest)
 Helper           # can edit help files
 Builder          # can edit the world
 Admin            # can administrate accounts
 Developer        # like superuser but affected by locks (highest)

(Besides being case-insensitive, hierarchical permissions also understand the plural form, so you could use Developers and Developer interchangeably).

There is also a Guest level below Player that is only active if settings.GUEST_ENABLED is set. The Guest is is never part of settings.PERMISSION_HIERARCHY.

When checking a hierarchical permission (using one of the methods to follow), you will pass checks for your level and all below you. That is, even if the check explicitly checks for “Builder” level access, you will actually pass if you have one of “Builder”, “Admin” or “Developer”. By contrast, if you check for a non-hierarchical permission, like “Blacksmith” you must have exactly that permission to pass.

Checking permissions

It’s important to note that you check for the permission of a puppeted Object (like a Character), the check will always first use the permissions of any Account connected to that Object before checking for permissions on the Object. In the case of hierarchical permissions (Admins, Builders etc), the Account permission will always be used (this stops an Account from escalating their permission by puppeting a high-level Character). If the permission looked for is not in the hierarchy, an exact match is required, first on the Account and if not found there (or if no Account is connected), then on the Object itself.

Checking with obj.permissions.check()

The simplest way to check if an entity has a permission is to check its PermissionHandler, stored as .permissions on all typeclassed entities.

if obj.permissions.check("Builder"):
    # allow builder to do stuff

if obj.permissions.check("Blacksmith", "Warrior"):
    # do stuff for blacksmiths OR warriors

if obj.permissions.check("Blacksmith", "Warrior", require_all=True):
    # only for those that are both blacksmiths AND warriors

Using the .check method is the way to go, it will take hierarchical permissions into account, check accounts/sessions etc.

Warning

Don't confuse `.permissions.check()` with `.permissions.has()`. The .has()
method checks if a string is defined specifically on that PermissionHandler.
It will not consider permission-hierarchy, puppeting etc. `.has` can be useful
if you are manipulating permissions, but use `.check` for access checking.

Lock funcs

While the PermissionHandler offers a simple way to check perms, Lock strings offers a mini-language for describing how something is accessed. The perm() lock function is the main tool for using Permissions in locks.

Let’s say we have a red_key object. We also have red chests that we want to unlock with this key.

perm red_key = unlocks_red_chests

This gives the red_key object the permission “unlocks_red_chests”. Next we lock our red chests:

lock red chest = unlock:perm(unlocks_red_chests)

When trying to unlock the red chest with this key, the chest Typeclass could then take the key and do an access check:

# in some typeclass file where chest is defined

class TreasureChest(Object):

  # ...

  def open_chest(self, who, tried_key):

      if not chest.access(who, tried_key, "unlock"):
          who.msg("The key does not fit!")
          return
      else:
          who.msg("The key fits! The chest opens.")
          # ...

There are several variations to the default perm lockfunc:

• perm_above - requires a hierarchical permission higher than the one provided. Example: "edit: perm_above(Player)"

• pperm - looks only for permissions on Accounts, never at any puppeted objects (regardless of hierarchical perm or not).

• pperm_above - like perm_above, but for Accounts only.

Some examples

Adding permissions and checking with locks

    account.permissions.add("Builder")
    account.permissions.add("cool_guy")
    account.locks.add("enter:perm_above(Player) and perm(cool_guy)")
    account.access(obj1, "enter") # this returns True!

An example of a puppet with a connected account:

    account.permissions.add("Player")
    puppet.permissions.add("Builders")
    puppet.permissions.add("cool_guy")
    obj2.locks.add("enter:perm_above(Accounts) and perm(cool_guy)")

    obj2.access(puppet, "enter") # this returns False, since puppet permission
                                 # is lower than Account's perm, and perm takes
                                 # precedence.

Superusers

There is normally only one superuser account and that is the one first created when starting Evennia (User #1). This is sometimes known as the “Owner” or “God” user. A superuser has more than full access - it completely bypasses all locks and will always pass the PermissionHandler.check() check. This allows for the superuser to always have access to everything in an emergency. But it could also hide any eventual errors you might have made in your lock definitions. So when trying out game systems you should either use quelling (see below) or make a second Developer-level character that does not bypass such checks.

Quelling

The quell command can be used to enforce the perm() lockfunc to ignore permissions on the Account and instead use the permissions on the Character only. This can be used e.g. by staff to test out things with a lower permission level. Return to the normal operation with unquell. Note that quelling will use the smallest of any hierarchical permission on the Account or Character, so one cannot escalate one’s Account permission by quelling to a high-permission Character. Also the superuser can quell their powers this way, making them affectable by locks.