1 /++ 2 The purpose of this small library is to perform automatic compile-time or 3 run-time dimensional checking when dealing with quantities and units. 4 5 There is no actual distinction between units and quantities, so there are no 6 distinct quantity and unit types. All operations are actually done on 7 quantities. For example, `meter` is both the unit _meter_ and the quantity _1m_. 8 New quantities can be derived from other ones using operators or dedicated 9 functions. 10 11 Quantities can be parsed from strings at run time and compile time. 12 13 The main SI units and prefixes are predefined. Units with other dimensions can 14 be defined by the user. 15 16 Copyright: Copyright 2013-2018, Nicolas Sicard. 17 License: Boost License 1.0. 18 +/ 19 module quantities; 20 21 public import quantities.compiletime; 22 public import quantities.runtime; 23 public import quantities.common; 24 public import quantities.parsing; 25 public import quantities.si; 26 27 /// Synopsis at compile-time 28 @("Synopsis at compile-time") 29 unittest 30 { 31 import quantities.compiletime; 32 import quantities.si; 33 34 // Define a quantity from SI units 35 auto distance = 384_400 * kilo(meter); 36 37 // Define a quantity from a string 38 auto speed = si!"299_792_458 m/s"; 39 // Define a type for a quantity 40 alias Speed = typeof(speed); 41 42 // Calculations on quantities 43 auto calculateTime(Length d, Speed s) 44 { 45 return d / s; 46 } 47 Time time = calculateTime(distance, speed); 48 49 // Dimensions are checked at compile time for consistency 50 assert(!__traits(compiles, distance + speed)); 51 52 // Format a quantity with a format specification known at compile-time 53 assert(siFormat!"%.3f s"(time) == "1.282 s"); 54 } 55 56 /// Synopsis at run-time 57 @("Synopsis at run-time") 58 unittest 59 { 60 import quantities.runtime; 61 import quantities.si; 62 import std.exception : assertThrown; 63 64 // Define a quantity from SI units (using the helper function `qVariant`) 65 auto distance = qVariant(384_400 * kilo(meter)); 66 67 // Define a quantity from a string 68 auto speed = parseSI("299_792_458 m/s"); 69 70 // Calculations on quantities (checked at compile time for consistency) 71 QVariant!double calculateTime(QVariant!double d, QVariant!double s) 72 { 73 return d / s; 74 } 75 auto time = calculateTime(distance, speed); 76 77 // Dimensions are checked at run time for consistency 78 assertThrown!DimensionException(distance + speed); 79 80 // Format a quantity with a format specification known at run-time 81 assert(siFormat("%.3f s", time) == "1.282 s"); 82 }