Alias

alias is a console command to define an alias, that is, a shortcut to one or more commands. Aliases may overwrite previously defined aliases.

Aliases will only act for the engine session they were defined in.

Usage

alias
alias <name> <command>
alias <name> "<command1>; <command2>; ..."

If no parameters are given, the game prints Current alias commands: followed by a list of all existing aliases and their values, if any. They appear in the order in which they were defined for the first time, starting with the newest.

The first parameter is the alias name (max. 31 characters) and all subsequent parameters are concatenated with a space character to form the command that the alias name will be associated with (max. 1023 characters). Passing no command behaves like passing the empty command.

Invoking the name of an alias like a command (after it has been defined with the alias command) will execute its associated command; Passing parameters has no effect.

The name of a new alias may not equal any existing console variable or console command. If the alias already exists, its associated command will be overwritten.

Examples

After running the command alias foo echo bar, typing foo in the console will execute echo bar.

After running the command alias foo, typing foo in the console will no longer do anything.

An example of an alias that toggles zoom. Running ZoomToggle will alternate between running +zoom and -zoom

alias ZoomON "+zoom; alias ZoomToggle ZoomOFF" alias ZoomOFF "-zoom; alias ZoomToggle ZoomON" alias ZoomToggle ZoomON

An example of using aliases to increment/decrement the field of view.

alias fov_85 "fov 85; alias fovIN; alias fovOUT fov_90" alias fov_90 "fov 90; alias fovIN fov_85; alias fovOUT fov_95" alias fov_95 "fov 95; alias fovIN fov_90; alias fovOUT" alias fovIN fov_85 alias fovOUT fov_95

Tip:In such cases, the commands incrementvar and multvar go without the definition of numerous aliases and therefore cause much less redundance:

alias fovIN  incrementvar fov 85 95 -5
alias fovOUT incrementvar fov 85 95  5

Alias names may also use the prefixes + and -, see bind#Syntax. A common use of alias is to change keybindings when a key is pressed or unpressed. For example, the following aliases can be used to make Alt+F4 exit the engine (whereas F4 alone will not):

alias +alt_pressed bind f4 exit
alias -alt_pressed unbind f4
bind alt +alt_pressed // note that pressing Alt executes +alt_pressed and releasing Alt executes -alt_pressed

Technical details

Each alias is a struct consisting of a name, a command string value and a reference to the next alias next.

To iterate over all existing aliases, the game stores a reference to some "first" alias. When a new alias is created, it is inserted as the first element. When iterating over all aliases (such as when printing them via the command alias), the alias that was created first will be the last element.

Advanced uses

Ignoring the limitation that there can only be a predefined maximum number of aliases, the alias command alone makes the source console Turing complete. In other words, it is able to simulate any computer calculation, meaning a command can be run based on an arbitrarily complex way that aliased commands were invoked. For example, an alias can run another command if the amount of times the alias was invoked previously was prime. There are many uses that are more practical.

If the limit of a predefined maximum number of aliases is not ignored, the source console is only able to simulate a finite-state machine. However, due to how the alias command can simulate a finite-state machine, it negates the typical drawback of mathematical operations requiring extremely large quantities of states. This is because, when the layer of abstraction to imagine a set of aliases as a finite-state machine is added, it is assumed that the results of inputs (contents of aliases) are not changed by default upon a transition. In other words, if state A dictates that input 1 will set the machine into state B, and input 2 of state A will set the machine into state C, then after invoking input 1, while the machine is indeed set to state B, inputs 1 and 2 still set the machine into states B and C, respectively, unless state B explicitly changes the functions of the inputs. The following example helps illustrate this:

alias state_A "alias input_1 state_B; alias input_2 state_C; alias input_3 state_D" alias state_B alias input_3 state_B

Here, after state A is activated, followed by input 1 firing, the functions of inputs 1 and 2 persist after state B becomes the current state. This attribute of transitions persisting between states until redefined allows for enumerations. A set of binary enumerations may be used to store data, which may be manipulated according to logic, allowing for reasonably efficient mathematical operations and comparisons of any data type, such as integers, doubles, or floats, all of which may be signed or unsigned, and of any length. Compare the ability to store a 32-bit value with 32 binary enumerations to a traditional finite-state machine's requirement of 2³² states to store an equivalent amount of data.