76 lines
3.1 KiB
C#
76 lines
3.1 KiB
C#
// Animancer // https://kybernetik.com.au/animancer // Copyright 2018-2024 Kybernetik //
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using System;
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using UnityEngine;
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using Object = UnityEngine.Object;
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namespace Animancer
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{
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/// <summary>
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/// Holds an instance of <typeparamref name="T"/> which is automatically created
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/// using its parameterless constructor when first accessed.
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/// </summary>
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/// <remarks>
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/// Don't use classes that inherit from <see cref="Object"/> as <typeparamref name="T"/>.
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/// <para></para>
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/// This is close to the "Singleton Programming Pattern", except it can't prevent additional instances of
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/// <typeparamref name="T"/> from being created elsewhere.
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/// </remarks>
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/// https://kybernetik.com.au/animancer/api/Animancer/Static_1
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public static class Static<T>
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where T : class, new()
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{
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/************************************************************************************************************************/
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/// <summary>
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/// An instance of <typeparamref name="T"/> which is automatically created
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/// using its parameterless constructor when first accessed.
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/// </summary>
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public static readonly T Instance = new();
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/************************************************************************************************************************/
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/// <summary>Ensures that the <see cref="Instance"/> has been created without immediately using it.</summary>
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public static void Initialize() { }
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/************************************************************************************************************************/
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#if UNITY_ASSERTIONS
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static Static()
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{
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if (Instance is Object)
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{
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Debug.LogError(
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$"{typeof(Static<T>).GetNameCS()} type is invalid:" +
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$" {nameof(UnityEngine)}.{nameof(Object)} types require special memory management by Unity" +
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$" which may cause problems when used with this system.",
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Instance as Object);
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}
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}
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#endif
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/************************************************************************************************************************/
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/// <summary>[Assert-Conditional]
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/// Call this in the constructor of <typeparamref name="T"/> to make sure there is only one instance.
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/// </summary>
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[System.Diagnostics.Conditional(Strings.Assertions)]
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public static void AssertSingularity()
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{
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#if UNITY_ASSERTIONS
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// If the static instance has already been set, then this is not the first one to be created.
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if (Instance != null)
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{
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var name = typeof(T).GetNameCS();
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throw new InvalidOperationException(
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$"Multiple {name} objects have been created." +
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$"\nUse Static<{name}>.Instance instead of creating your own instances.");
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}
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#endif
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}
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/************************************************************************************************************************/
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}
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}
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