/// <summary>
/// Creates an atom that store the value.
/// </summary>
/// <param name="value">Initial value.</param>
/// <param name="callbacks">Atom lifetime callbacks.</param>
/// <param name="comparer">Value comparer used for reconciling.</param>
/// <param name="debugName">Debug name for this atom.</param>
/// <typeparam name="T">Atom value type.</typeparam>
/// <returns>Created atom.</returns>
/// <example>
///
/// var counter = Atom.Value();
/// counter.Value += 1;
///
/// Debug.Log(counter.Value);
///
/// </example>
public static MutableAtom <T> Value <T>(
T value,
IAtomCallbacks callbacks = null,
IEqualityComparer <T> comparer = null,
string debugName = null)
{
return(new ValueAtom <T>(debugName, value, callbacks, comparer));
}
/// <summary>
/// Creates an atom that compute its value by a function.<br/>
/// </summary>
/// <remarks>
/// Computed values can be used to derive information from other atoms.
/// They evaluate lazily, caching their output and only recomputing
/// if one of the underlying atoms has changed. If they are not observed
/// by anything, they suspend entirely.<br/>
/// <br/>
/// Conceptually, they are very similar to formulas in spreadsheets,
/// and can't be underestimated. They help in reducing the amount of state
/// you have to store and are highly optimized. Use them wherever possible.
/// </remarks>
/// <param name="pull">Function for pulling value.</param>
/// <param name="keepAlive">Should an atom keep its value cached when there are no subscribers?</param>
/// <param name="requiresReaction">Should an atom print warnings when its values are tried to be read outside of the reaction?</param>
/// <param name="callbacks">Atom lifetime callbacks.</param>
/// <param name="comparer">Value comparer used for reconciling.</param>
/// <param name="debugName">Debug name for this atom.</param>
/// <typeparam name="T">Atom value type.</typeparam>
/// <returns>Created atom.</returns>
/// <example>
///
/// var a = Atom.Value(1);
/// var b = Atom.Value(2);
///
/// var sum = Atom.Computed(() => a.Value + b.Value);
///
/// Debug.Log(sum.Value);
///
/// </example>
public static Atom <T> Computed <T>(
AtomPull <T> pull,
bool keepAlive = false,
bool requiresReaction = false,
IAtomCallbacks callbacks = null,
IEqualityComparer <T> comparer = null,
string debugName = null)
{
return(new ComputedAtom <T>(debugName, pull, null, keepAlive, requiresReaction, callbacks, comparer));
}
internal ValueAtom(
string debugName,
T value,
IAtomCallbacks callbacks,
IEqualityComparer <T> comparer = null)
: base(debugName, false, callbacks)
{
_value = value;
_comparer = comparer ?? EqualityComparer <T> .Default;
}
internal ComputedAtom(
string debugName,
[NotNull] AtomPull <T> pull,
AtomPush <T> push = null,
bool keepAlive = false,
bool requiresReaction = false,
IAtomCallbacks callbacks = null,
IEqualityComparer <T> comparer = null)
: base(debugName, keepAlive, callbacks)
{
_pull = pull ?? throw new ArgumentNullException(nameof(pull));
_push = push;
_comparer = comparer ?? EqualityComparer <T> .Default;
_requiresReaction = requiresReaction;
}