Coding/Cvars

Classes that handle Cvars are defined in daemon/src/common/Cvar.h.

Registering Cvars from the sources

Instantiate an object of the correct class with static storage.

Example

static Cvar::Cvar<std::string> some_cvar(
    "cvar_name",
    "Cvar description",
    Cvar::NONE,
    "default value"
);

Log::Debug("The value of the cvar is %s", some_cvar.Get());
// Also possible is *some_cvar instead of Get

Cvar types

Cvar::Cvar

Allows to define cvars that can hold simple values, while it is a template it requires a parser and serializer for the type it should contain.

By default, these types are supported out of the box:

• Cvar::Cvar<bool>
• Cvar::Cvar<int>
• Cvar::Cvar<float>
• Cvar::Cvar<std::string>

Cvar::Callback

This is a curiously recurring wrapper that allows execution of arbitrary code on cvar changes.

Example

static Cvar::Callback<Cvar::Cvar<std::string>> best(
	"best",
	"Who is the best?",
	Cvar::NONE,
	"",
	[](const std::string& name){
		Log::Notice("%s is the best", name);
	}
);

Cvar::Callback

This is a curiously recurring wrapper that allows execution of arbitrary code on cvar changes.

Example

static Cvar::Callback<Cvar::Cvar<std::string>> best(
	"best",
	"Who is the best?",
	Cvar::NONE,
	"",
	[](const std::string& name){
		Log::Notice("%s is the best", name);
	}
);

Cvar::Modified

This is a curiously recurring wrapper that allows querying whether the value has changed.

Cvar::Range

This is a curiously recurring wrapper that limits cvars whose value_type has a meaningful ordering relation to be within the given range.

Example

static Cvar::Range<Cvar::Cvar<int>> percent(
	"percent",
	"%",
	Cvar::NONE,
	100, // default
	0,   // min
	100  // max (inclusive)
);

Customizing

Creating customized cvar types with special restrictions is pretty straightforward.

Example (Combining existing classes)

static Cvar::Range<Cvar::Callback<Cvar::Cvar<int>>> bottles_of_beer(
	"bottles_of_beer",
	"Number of bottles of beer on the wall",
	Cvar::NONE,
	99,
	0,
	99,
	[](int n) {
		Log::Notice("%-2d bottles of beer on the wall, %2d bottles of beer.", n, n);
		if ( n > 0 )
		{
			Log::Notice("Take one down, pass it around, %3d bottles of beer on the wall...", n-1);
			bottles_of_beer.Set(n-1);
		}
	}
);

Example (Custom class)

class HexCvar : public Cvar::Cvar<std::string>
{
private:
	::Cvar::OnValueChangedResult Validate(const value_type& value) override
	{
		if ( std::all_of( value.begin(), value.end(), Str::cisxdigit ) )
		{
			return { true, "" };
		}
		return { false, "Must be hex!" };
	}
};

static HexCvar cvar_hex(
	"cl_hexString",
	"Must be hex",
	Cvar::NONE,
	""
);