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73 lines
2.5 KiB
73 lines
2.5 KiB
5 years ago
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/**
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* Singleton is an auxiliary class, meant to be used as a base for others,
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* that allows for only one instance of it to exist.
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* To make sure your child class properly works, either don't overload
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* 'PreBeginPlay' or make sure to call it's parent's version.
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* Copyright 2019 Anton Tarasenko
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*------------------------------------------------------------------------------
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* This file is part of Acedia.
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*
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* Acedia is free software: you can redistribute it and/or modify
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* it under the terms of the GNU General Public License as published by
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* the Free Software Foundation, version 3 of the License, or
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* (at your option) any later version.
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*
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* Acedia is distributed in the hope that it will be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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* GNU General Public License for more details.
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*
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* You should have received a copy of the GNU General Public License
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* along with Acedia. If not, see <https://www.gnu.org/licenses/>.
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*/
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class Singleton extends Actor
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abstract;
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// Default value of this variable will store one and only existing version\
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// of actor of this class.
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var private Singleton activeInstance;
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// Setting default value of this variable to 'true' prevents creation of
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// a singleton, even if no instances of it exist.
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// Only a default value is ever used.
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var protected bool blockSpawning;
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public final static function Singleton GetInstance()
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{
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if (default.activeInstance != none && default.activeInstance.bPendingDelete)
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return none;
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return default.activeInstance;
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}
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public final static function bool IsSingletonCreationBlocked()
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{
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return default.blockSpawning;
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}
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// Make sure only one instance of 'Singleton' exists at any point in time.
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// If you overload this function in any child class -
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// first call this version of the method and then check if
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// you are about to be deleted 'bDeleteMe == true':
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// ____________________________________________________________________________
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// | super.PreBeginPlay();
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// | // ^^^ If singleton wasn't already created, - only after that call
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// | // will instance, returned by 'GetInstance()', be set.
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// | if (bDeleteMe)
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// | return;
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// |___________________________________________________________________________
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event PreBeginPlay()
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{
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if (default.blockSpawning || GetInstance() != none)
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{
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Destroy();
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}
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else
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{
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default.activeInstance = self;
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}
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}
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defaultproperties
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{
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blockSpawning = false
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}
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