ConVar Reference
This script demonstrates ConVar refences. These are the preferred way to interact with ConVars, and the only way to interact with ones registered outside of your script.
[ClientCommand("cl_example_cvarref")]
void MyCvarRefDemo(const CommandArgs@ args)
{
ConVarRef intensity("r_portal_light_intensity");
Msg("is r_protal_light_intensity valid? " + intensity.GetBool() + "\n");
Msg("current val: " + intensity.GetFloat() + "\n");
intensity.SetValue(1);
Msg("New val: " + intensity.GetFloat() + "\n");
ConVarRef invalid_cvar("my_invalid_thingy");
Msg("is my_invalid_thingy valid? " + invalid_cvar.IsValid() + "\n");
}