SourcePawn Basics - Customization through ConVars

Prerequisite: This guide assumes you have read Introduction to SourcePawn and Introduction to SourceMod Plugins.

Server owners like customization. Lots of customization. So, how do you add customization to your plugin? The simplest route is by adding ConVars.

ConVars / CVars

Console Variables (ConVars or CVars for short) are server settings that can be changed by server owners. Anything you put into your server's server.cfg file is a convar.

Just like the server itself, plugins can create their own convars. A convar is different from a regular variable in that it is visible outside your plugin.

Creating your own ConVars

ConVars should always be created in OnPluginStart.

When you create your ConVars, they should name them consistently. A good naming practice is nameofplugin_settingname or nameofplugin_setting_name.

ConVars are created via the CreateConVar command. The order of arguments are:

name 

The convar name, preferably using the naming scheme above

defaultValue 

A string with the default value.

description 

A description of what this ConVar does for the find or listcvars commands

flags 

An | separate list of convar flags

hasMin 

A bool stating whether the min argument exists

min 

A Float with the minimum allowed value

hasMax 

A bool stating whether the max argument exists

min 

A Float with the maximum allowed value

Useful ConVar Flags

• FCVAR_NONE - The default, no flags set.
• FCVAR_PROTECTED - Used for passwords. Don't send this value to clients who ask for it, only send 1 if it's set or 0 if it isn't.
• FCVAR_SPONLY - Not changeable in multiplayer
• FCVAR_NOTIFY - Players are informed when this ConVar changes. ConVars marked with this attribute are also visible to tracking services.
• FCVAR_NEVER_AS_STRING - Don't try to print this out
• FCVAR_DONTRECORD - Not recorded in demo files. Also, not recorded in AutoExecConfig files.
• FCVAR_PLUGIN - Defined by a 3rd Party plugin. SourceMod probably adds this already even if you don't.

Locating ConVars from the game or other plugins

Looking up plugins is an expensive operation and should be done just once if you can help it.

The best location to do this is in the OnAllPluginsLoaded callback.

For example, here is how to look up the mp_autoteambalance ConVar

 new Handle:g_hAutoTeamBalance;
 
 public OnAllPluginsLoaded()
 {
     g_hAutoTeamBalance = FindConVar("mp_autoteambalance");
 }

Reading and Setting ConVars

ConVars can be read as several different kinds of values: cell (int), bool, Float, or String.

Here is how you read a bool ConVar:

     new bool:value = GetConVarInt(g_hAutoTeamBalance);

and to set the same ConVar:

     SetConVarInt(g_hAutoTeamBalance, true);

Int and Floats work roughly the same way with GetConVarInt / GetConVarFloat / SetConVarInt / SetConVarFloat.

Strings work the same for setting, but reading a String ConVar works slightly differently:

   decl String:value[64];
   GetConVarString(myConVar, value, sizeof(value));

This pattern is common for functions that do String manipulations.

Standard ConVars

There are a few standard ConVars that most plugins have.

The first is a version ConVar. Unlike most ConVars, you don't need to store the Handle of this one as you never need to read its value.

Normally, your version ConVar will look a little like this.

 #define VERSION "1.0"
 
 public OnPluginStart()
 {
     CreateConVar("test_version", VERSION, "Test Plugin version", FCVAR_NOTIFY|FCVAR_DONTRECORD|FCVAR_PLUGIN|FCVAR_SPONLY);
 }

VERSION is defined here so that it can be used in the plugin's myinfo struct as well.

A second common ConVar is the enable ConVar.

 new Handle:g_hEnabled;
 
 public OnPluginStart()
 {
     g_hEnabled = CreateConVar("test_enable", "1", "Test Plugin Enable", FCVAR_NOTIFY|FCVAR_DONTRECORD, true, 0.0, true, 1.0);
 }

Note that FCVAR_DONTRECORD is still present. This is a recommendation in case your plugin has an AutoExecConfig file.

You would then read this cvar with

     if (GetConVarBool(g_hEnabled))
     {
         // The plugin is currently enabled
     }