Add UnitsNetSetup to hold global static state

Fix static init racing condition by replacing {get;} with =>

UnitsNet/CustomCode/Quantity.cs

@@ -9,15 +9,7 @@ namespace UnitsNet
 {
     public partial class Quantity
     {
-        static Quantity()
-        {
-            Default = new QuantityInfoLookup();
-        }
-
-        private static QuantityInfoLookup Default
-        {
-            get;
-        }
+        private static QuantityInfoLookup Default => UnitsNetSetup.Default.QuantityInfoLookup;
 
         /// <summary>
         /// All enum value names of <see cref="Infos"/>, such as "Length" and "Mass".

UnitsNet/CustomCode/QuantityParser.cs

@@ -37,7 +37,8 @@ public class QuantityParser
         /// <summary>
         ///     The default instance of <see cref="QuantityParser"/>, which uses <see cref="UnitAbbreviationsCache.Default"/> unit abbreviations.
         /// </summary>
-        public static QuantityParser Default { get; }
+        [Obsolete("Use UnitsNetSetup.Default.QuantityParser instead.")]
+        public static QuantityParser Default => UnitsNetSetup.Default.QuantityParser;
 
         /// <summary>
         ///     Creates an instance of <see cref="QuantityParser"/>, optionally specifying an <see cref="UnitAbbreviationsCache"/>
@@ -50,11 +51,6 @@ public QuantityParser(UnitAbbreviationsCache? unitAbbreviationsCache = null)
             _unitParser = new UnitParser(_unitAbbreviationsCache);
         }
 
-        static QuantityParser()
-        {
-            Default = new QuantityParser(UnitAbbreviationsCache.Default);
-        }
-
         /// <summary>
         ///     Parses a quantity from a string, such as "1.2 kg" to <see cref="Length"/> or "100 cm" to <see cref="Mass"/>.
         /// </summary>

UnitsNet/CustomCode/UnitAbbreviationsCache.cs

@@ -30,23 +30,48 @@ public sealed class UnitAbbreviationsCache
         /// <summary>
         ///     The static instance used internally for ToString() and Parse() of quantities and units.
         /// </summary>
-        public static UnitAbbreviationsCache Default { get; }
+        [Obsolete("Use UnitsNetSetup.Default.UnitAbbreviations instead.")]
+        public static UnitAbbreviationsCache Default => UnitsNetSetup.Default.UnitAbbreviations;
 
         private QuantityInfoLookup QuantityInfoLookup { get; }
 
         /// <summary>
         ///     Create an instance of the cache and load all the abbreviations defined in the library.
         /// </summary>
+        // TODO Change this to create an empty cache in v6: https://github.com/angularsen/UnitsNet/issues/1200
+        [Obsolete("Use CreateDefault() instead to create an instance that loads the built-in units. The default ctor will change to create an empty cache in UnitsNet v6.")]
         public UnitAbbreviationsCache()
+            : this(new QuantityInfoLookup(Quantity.ByName.Values))
         {
-            QuantityInfoLookup= new QuantityInfoLookup();
         }
 
-        static UnitAbbreviationsCache()
+        /// <summary>
+        ///     Creates an instance of the cache and load all the abbreviations defined in the library.
+        /// </summary>
+        /// <remarks>
+        ///     Access type is <c>internal</c> until this class is matured and ready for external use.
+        /// </remarks>
+        internal UnitAbbreviationsCache(QuantityInfoLookup quantityInfoLookup)
         {
-            Default = new UnitAbbreviationsCache();
+            QuantityInfoLookup = quantityInfoLookup;
         }
 
+        /// <summary>
+        ///     Create an instance with empty cache.
+        /// </summary>
+        /// <remarks>
+        ///     Workaround until v6 changes the default ctor to create an empty cache.<br/>
+        /// </remarks>
+        /// <returns>Instance with empty cache.</returns>
+        // TODO Remove in v6: https://github.com/angularsen/UnitsNet/issues/1200
+        public static UnitAbbreviationsCache CreateEmpty() => new(new QuantityInfoLookup(new List<QuantityInfo>()));
+
+        /// <summary>
+        ///     Create an instance of the cache and load all the built-in unit abbreviations defined in the library.
+        /// </summary>
+        /// <returns>Instance with default abbreviations cache.</returns>
+        public static UnitAbbreviationsCache CreateDefault() => new(new QuantityInfoLookup(Quantity.ByName.Values));
+
         /// <summary>
         /// Adds one or more unit abbreviation for the given unit enum value.
         /// This is used to dynamically add abbreviations for existing unit enums such as <see cref="UnitsNet.Units.LengthUnit"/> or to extend with third-party unit enums

UnitsNet/CustomCode/UnitParser.cs

@@ -23,22 +23,19 @@ public sealed class UnitParser
         ///     The default static instance used internally to parse quantities and units using the
         ///     default abbreviations cache for all units and abbreviations defined in the library.
         /// </summary>
-        public static UnitParser Default { get; }
+        [Obsolete("Use UnitsNetSetup.Default.UnitParser instead.")]
+        public static UnitParser Default => UnitsNetSetup.Default.UnitParser;
 
         /// <summary>
         ///     Create a parser using the given unit abbreviations cache.
         /// </summary>
         /// <param name="unitAbbreviationsCache"></param>
+        // TODO Change this to not fallback to built-in units abbreviations when given null, in v6: https://github.com/angularsen/UnitsNet/issues/1200
         public UnitParser(UnitAbbreviationsCache? unitAbbreviationsCache)
         {
             _unitAbbreviationsCache = unitAbbreviationsCache ?? UnitAbbreviationsCache.Default;
         }
 
-        static UnitParser()
-        {
-            Default = new UnitParser(UnitAbbreviationsCache.Default);
-        }
-
         /// <summary>
         /// Parses a unit abbreviation for a given unit enumeration type.
         /// Example: Parse&lt;LengthUnit&gt;("km") => LengthUnit.Kilometer

UnitsNet/CustomCode/UnitsNetSetup.cs

@@ -0,0 +1,85 @@
+// Licensed under MIT No Attribution, see LICENSE file at the root.
+// Copyright 2013 Andreas Gullberg Larsen ([email protected]). Maintained at https://github.com/angularsen/UnitsNet.
+
+using System.Collections.Generic;
+using UnitsNet.Units;
+
+namespace UnitsNet;
+
+/// <summary>
+///     UnitsNet setup of quantities, units, unit abbreviations and conversion functions.<br />
+///     <br />
+///     For normal use, <see cref="Default" /> is used and can be manipulated to add new units or change default unit
+///     abbreviations.<br />
+///     Alternatively, a setup instance may be provided for most static methods, such as
+///     <see cref="Quantity.Parse(System.Type,string)" /> and
+///     <see cref="QuantityFormatter.Format{TUnitType}(UnitsNet.IQuantity{TUnitType},string)" />.
+/// </summary>
+public sealed class UnitsNetSetup
+{
+    static UnitsNetSetup()
+    {
+        var unitConverter = UnitConverter.CreateDefault();
+        ICollection<QuantityInfo> quantityInfos = Quantity.ByName.Values;
+
+        Default = new UnitsNetSetup(quantityInfos, unitConverter);
+    }
+
+    /// <summary>
+    ///     Create a new UnitsNet setup with the given quantities, their units and unit conversion functions between units.
+    /// </summary>
+    /// <param name="quantityInfos">The quantities and their units to support for unit conversions, Parse() and ToString().</param>
+    /// <param name="unitConverter">The unit converter instance.</param>
+    public UnitsNetSetup(ICollection<QuantityInfo> quantityInfos, UnitConverter unitConverter)
+    {
+        var quantityInfoLookup = new QuantityInfoLookup(quantityInfos);
+        var unitAbbreviations = new UnitAbbreviationsCache(quantityInfoLookup);
+
+        UnitConverter = unitConverter;
+        UnitAbbreviations = unitAbbreviations;
+        UnitParser = new UnitParser(unitAbbreviations);
+        QuantityParser = new QuantityParser(unitAbbreviations);
+        QuantityInfoLookup = quantityInfoLookup;
+    }
+
+    /// <summary>
+    ///     The global default UnitsNet setup of quantities, units, unit abbreviations and conversion functions.
+    ///     This setup is used by default in static Parse and ToString methods of quantities unless a setup instance is
+    ///     provided.
+    /// </summary>
+    /// <remarks>
+    ///     Manipulating this instance, such as adding new units or changing default unit abbreviations, will affect most
+    ///     usages of UnitsNet in the
+    ///     current AppDomain since the typical use is via static members and not providing a setup instance.
+    /// </remarks>
+    public static UnitsNetSetup Default { get; }
+
+    /// <summary>
+    ///     Converts between units of a quantity, such as from meters to centimeters of a given length.
+    /// </summary>
+    public UnitConverter UnitConverter { get; }
+
+    /// <summary>
+    ///     Maps unit enums to unit abbreviation strings for one or more cultures, used by ToString() and Parse() methods of
+    ///     quantities.
+    /// </summary>
+    public UnitAbbreviationsCache UnitAbbreviations { get; }
+
+    /// <summary>
+    ///     Parses units from strings, such as <see cref="LengthUnit.Centimeter" /> from "cm".
+    /// </summary>
+    public UnitParser UnitParser { get; }
+
+    /// <summary>
+    ///     Parses quantities from strings, such as parsing <see cref="Mass" /> from "1.2 kg".
+    /// </summary>
+    internal QuantityParser QuantityParser { get; }
+
+    /// <summary>
+    ///     The quantities and units that are loaded.
+    /// </summary>
+    /// <remarks>
+    ///     Access type is <c>internal</c> until this class is matured and ready for external use.
+    /// </remarks>
+    internal QuantityInfoLookup QuantityInfoLookup { get; }
+}

UnitsNet/QuantityInfoLookup.cs

@@ -9,24 +9,27 @@ namespace UnitsNet
     /// <summary>
     /// A collection of <see cref="QuantityInfo"/>.
     /// </summary>
-    public class QuantityInfoLookup
+    /// <remarks>
+    ///     Access type is <c>internal</c> until this class is matured and ready for external use.
+    /// </remarks>
+    internal class QuantityInfoLookup
     {
-        private readonly Lazy<QuantityInfo[]> InfosLazy;
-        private readonly Lazy<Dictionary<(Type, string), UnitInfo>> UnitTypeAndNameToUnitInfoLazy;
+        private readonly Lazy<QuantityInfo[]> _infosLazy;
+        private readonly Lazy<Dictionary<(Type, string), UnitInfo>> _unitTypeAndNameToUnitInfoLazy;
 
         /// <summary>
         /// New instance.
         /// </summary>
-        public QuantityInfoLookup()
+        /// <param name="quantityInfos"></param>
+        public QuantityInfoLookup(ICollection<QuantityInfo> quantityInfos)
         {
-            ICollection<QuantityInfo> quantityInfos = Quantity.ByName.Values;
             Names = quantityInfos.Select(qt => qt.Name).ToArray();
 
-            InfosLazy = new Lazy<QuantityInfo[]>(() => quantityInfos
+            _infosLazy = new Lazy<QuantityInfo[]>(() => quantityInfos
                 .OrderBy(quantityInfo => quantityInfo.Name)
                 .ToArray());
 
-            UnitTypeAndNameToUnitInfoLazy = new Lazy<Dictionary<(Type, string), UnitInfo>>(() =>
+            _unitTypeAndNameToUnitInfoLazy = new Lazy<Dictionary<(Type, string), UnitInfo>>(() =>
             {
                 return Infos
                     .SelectMany(quantityInfo => quantityInfo.UnitInfos
@@ -45,18 +48,18 @@ public QuantityInfoLookup()
         /// <summary>
         /// All quantity information objects, such as <see cref="Length.Info"/> and <see cref="Mass.Info"/>.
         /// </summary>
-        public QuantityInfo[] Infos => InfosLazy.Value;
+        public QuantityInfo[] Infos => _infosLazy.Value;
 
         /// <summary>
         /// Get <see cref="UnitInfo"/> for a given unit enum value.
         /// </summary>
-        public UnitInfo GetUnitInfo(Enum unitEnum) => UnitTypeAndNameToUnitInfoLazy.Value[(unitEnum.GetType(), unitEnum.ToString())];
+        public UnitInfo GetUnitInfo(Enum unitEnum) => _unitTypeAndNameToUnitInfoLazy.Value[(unitEnum.GetType(), unitEnum.ToString())];
 
         /// <summary>
         /// Try to get <see cref="UnitInfo"/> for a given unit enum value.
         /// </summary>
         public bool TryGetUnitInfo(Enum unitEnum, [NotNullWhen(true)] out UnitInfo? unitInfo) =>
-            UnitTypeAndNameToUnitInfoLazy.Value.TryGetValue((unitEnum.GetType(), unitEnum.ToString()), out unitInfo);
+            _unitTypeAndNameToUnitInfoLazy.Value.TryGetValue((unitEnum.GetType(), unitEnum.ToString()), out unitInfo);
 
         /// <summary>
         ///
@@ -65,7 +68,7 @@ public bool TryGetUnitInfo(Enum unitEnum, [NotNullWhen(true)] out UnitInfo? unit
         /// <param name="unitInfo"></param>
         public void AddUnitInfo(Enum unit, UnitInfo unitInfo)
         {
-            UnitTypeAndNameToUnitInfoLazy.Value.Add((unit.GetType(), unit.ToString()), unitInfo);
+            _unitTypeAndNameToUnitInfoLazy.Value.Add((unit.GetType(), unit.ToString()), unitInfo);
         }
 
         /// <summary>
@@ -77,6 +80,7 @@ public void AddUnitInfo(Enum unit, UnitInfo unitInfo)
         /// <exception cref="ArgumentException">Unit value is not a know unit enum type.</exception>
         public IQuantity From(QuantityValue value, Enum unit)
         {
+            // TODO Support custom units, currently only hardcoded built-in quantities are supported.
             return Quantity.TryFrom(value, unit, out IQuantity? quantity)
                 ? quantity
                 : throw new UnitNotFoundException($"Unit value {unit} of type {unit.GetType()} is not a known unit enum type. Expected types like UnitsNet.Units.LengthUnit. Did you pass in a custom enum type defined outside the UnitsNet library?");
@@ -93,6 +97,7 @@ public bool TryFrom(double value, Enum unit, [NotNullWhen(true)] out IQuantity?
                 return false;
             }
 
+            // TODO Support custom units, currently only hardcoded built-in quantities are supported.
             return Quantity.TryFrom((QuantityValue)value, unit, out quantity);
         }
 
@@ -112,23 +117,27 @@ public IQuantity Parse(IFormatProvider? formatProvider, Type quantityType, strin
             if (!typeof(IQuantity).IsAssignableFrom(quantityType))
                 throw new ArgumentException($"Type {quantityType} must be of type UnitsNet.IQuantity.");
 
+            // TODO Support custom units, currently only hardcoded built-in quantities are supported.
             if (Quantity.TryParse(formatProvider, quantityType, quantityString, out IQuantity? quantity))
                 return quantity;
 
             throw new UnitNotFoundException($"Quantity string '{quantityString}' could not be parsed to quantity '{quantityType}'.");
         }
 
         /// <inheritdoc cref="Quantity.TryParse(IFormatProvider,System.Type,string,out UnitsNet.IQuantity)"/>
-        public bool TryParse(Type quantityType, string quantityString, [NotNullWhen(true)] out IQuantity? quantity) =>
-            Quantity.TryParse(null, quantityType, quantityString, out quantity);
+        public bool TryParse(Type quantityType, string quantityString, [NotNullWhen(true)] out IQuantity? quantity)
+        {
+            // TODO Support custom units, currently only hardcoded built-in quantities are supported.
+            return Quantity.TryParse(null, quantityType, quantityString, out quantity);
+        }
 
         /// <summary>
         ///     Get a list of quantities that has the given base dimensions.
         /// </summary>
         /// <param name="baseDimensions">The base dimensions to match.</param>
         public IEnumerable<QuantityInfo> GetQuantitiesWithBaseDimensions(BaseDimensions baseDimensions)
         {
-            return InfosLazy.Value.Where(info => info.BaseDimensions.Equals(baseDimensions));
+            return _infosLazy.Value.Where(info => info.BaseDimensions.Equals(baseDimensions));
         }
     }
 }

UnitsNet/UnitConverter.cs

@@ -39,13 +39,8 @@ public sealed class UnitConverter
         /// The static instance used by Units.NET to convert between units. Modify this to add/remove conversion functions at runtime, such
         /// as adding your own third-party units and quantities to convert between.
         /// </summary>
-        public static UnitConverter Default { get; }
-
-        static UnitConverter()
-        {
-            Default = new UnitConverter();
-            RegisterDefaultConversions(Default);
-        }
+        [Obsolete("Use UnitsNetSetup.Default.UnitConverter instead.")]
+        public static UnitConverter Default => UnitsNetSetup.Default.UnitConverter;
 
         /// <summary>
         /// Creates a new <see cref="UnitConverter"/> instance.
@@ -64,6 +59,18 @@ public UnitConverter(UnitConverter other)
             ConversionFunctions = new ConcurrentDictionary<ConversionFunctionLookupKey, ConversionFunction>(other.ConversionFunctions);
         }
 
+        /// <summary>
+        ///     Create an instance of the unit converter with all the built-in unit conversions defined in the library.
+        /// </summary>
+        /// <returns>The unit converter.</returns>
+        public static UnitConverter CreateDefault()
+        {
+            var unitConverter = new UnitConverter();
+            RegisterDefaultConversions(unitConverter);
+
+            return unitConverter;
+        }
+
         private ConcurrentDictionary<ConversionFunctionLookupKey, ConversionFunction> ConversionFunctions
         {
             get;