quantity 0.3.0

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quantity #

Facilitates working with physical quantities such as angles, lengths, masses and temperatures.

In science and engineering it is critical to use units along with numerical values. For example, 5 meters per second is decidedly not the same speed as 5 feet per minute. Calculations must include units, implicitly or explicitly, to be correct and useful. This package provides classes for modeling quantities of specific types and their associated units as well as their use in calculations.

The International System of Units (often called 'SI' from its abbreviation in French) defines the quantity types, associated units and constants used by scientists and engineers around the world. This package models the SI base and derived quantities in its quantity_si library.

There are also many historical units, of course, that were around well before the SI came into existence. These can be found in the quantity_ext library.

The number library adds support for quantities having values of arbitrary precision and the quantity_range library adds special support for handling value ranges.

Together, these libraries give you the tools to maintain units discipline in your code and make Dart a more attractive option for many science and engineering applications by eliminating common mistakes and offering improved readability.

Quick start #

// Import the core library.
import 'package:quantity/quantity_si.dart';

// Construct an Angle in radians.
var ang = new Angle(rad: 1.1);

// Construct an Angle in degrees.
var ang2 = new Angle(deg: 270);

// Find the difference.
var diff = ang2 - ang;

// Display the result in degrees.
print(diff.valueInUnits(Angle.degrees);

Key Features #

  • Typed quantities (such as Length, Mass and Temperature) that are easy to construct and use in calculations.
  • Encourages use of standard units by isolating non-standard units in an extension library.
  • Support for relative standard uncertainty in quantity values and calculations.
  • Allows use of arbitrary precision values (as well as complex and imaginary values).
  • Provides access to the latest official constant values published by NIST.
  • Integration with Dart's existing Duration and DateTime classes.
  • Extensive set of quantity types and standard and non-standard units.
  • Support for untyped quantities having unusual dimensions with the MiscQuantity class.
  • Models quantity ranges, including special support for angle ranges and time spans.
  • Includes a mutable quantity with streams.
  • Metric prefixes for any unit.

0.3.0 #

  • Relaxed version constraint on package intl.

0.2.0+1 #

  • Dart 2 support.
  • Stricter typing.
  • Addressed many (but not all) analyzer items.

0.1.5 #

  • Upgraded dependencies: intl 0.14 and quiver 0.23

0.1.4 #

  • Added isScalar and isScalarSI to Dimensions and Quantity.
  • Extended use of type hints in dimensions for more efficient and accurate type determination during operations.
  • Generalized special handling of scalar quantities.

0.1.3+1 #

  • Fixed CHANGELOG.md formatting.

0.1.3 #

  • Added operator == and hashCode to quantity range classes.
  • Added toTypedQuantity to MiscQuantity.
  • Changed googol constant to arbitrary precision.
  • Renamed private _dimensions constructor to _internal in quantities.

0.1.2 #

  • Precise isInteger and _limitPrecision fixes.
  • hashCode testing for quantity objects (esp. Scalar)

0.1.1 #

  • Temperature, TemperatureInterval tests, tweaks, bug fixes.

0.1.0 #

  • Initial version.

Use this package as a library

1. Depend on it

Add this to your package's pubspec.yaml file:


dependencies:
  quantity: ^0.3.0

2. Install it

You can install packages from the command line:

with pub:


$ pub get

with Flutter:


$ flutter pub get

Alternatively, your editor might support pub get or flutter pub get. Check the docs for your editor to learn more.

3. Import it

Now in your Dart code, you can use:


import 'package:quantity/quantity.dart';
  
Popularity:
Describes how popular the package is relative to other packages. [more]
62
Health:
Code health derived from static analysis. [more]
75
Maintenance:
Reflects how tidy and up-to-date the package is. [more]
75
Overall:
Weighted score of the above. [more]
68
Learn more about scoring.

We analyzed this package on Apr 3, 2020, and provided a score, details, and suggestions below. Analysis was completed with status completed using:

  • Dart: 2.7.1
  • pana: 0.13.6

Health suggestions

Fix lib/quantity_si.dart. (-25 points)

Analysis of lib/quantity_si.dart reported 81 hints, including:

line 103 col 18: Unnecessary new keyword.

line 111 col 60: Unnecessary new keyword.

line 113 col 7: Unnecessary new keyword.

line 115 col 7: Unnecessary new keyword.

line 117 col 7: Unnecessary new keyword.

Fix lib/src/ext/scalar_ext.dart. (-24.47 points)

Analysis of lib/src/ext/scalar_ext.dart reported 56 hints, including:

line 10 col 35: Unnecessary new keyword.

line 13 col 34: Unnecessary new keyword.

line 16 col 32: Unnecessary new keyword.

line 19 col 33: Unnecessary new keyword.

line 22 col 32: Unnecessary new keyword.

Fix lib/src/number/complex.dart. (-24.10 points)

Analysis of lib/src/number/complex.dart reported 55 hints, including:

line 16 col 16: Unnecessary new keyword.

line 17 col 21: Unnecessary new keyword.

line 17 col 44: Unnecessary new keyword.

line 20 col 52: Unnecessary new keyword.

line 22 col 15: Unnecessary new keyword.

Fix additional 135 files with analysis or formatting issues. (-516.05 points)

Additional issues in the following files:

  • lib/src/number/imaginary.dart (51 hints)
  • lib/src/number/real.dart (50 hints)
  • lib/src/number/precise.dart (49 hints)
  • lib/src/ext/length_ext.dart (46 hints)
  • lib/domain/thermodynamic.dart (42 hints)
  • lib/src/ext/time_instant_ext.dart (41 hints)
  • lib/src/ext/mass_ext.dart (38 hints)
  • lib/src/ext/volume_ext.dart (29 hints)
  • lib/range/angle_range.dart (28 hints)
  • lib/src/number/integer.dart (27 hints)
  • lib/src/ext/energy_ext.dart (23 hints)
  • lib/src/ext/angle_ext.dart (18 hints)
  • lib/src/ext/mutable/mutable_quantity.dart (17 hints)
  • lib/src/si/dimensions.dart (17 hints)
  • lib/domain/astronomical.dart (14 hints)
  • lib/src/si/quantity.dart (14 hints)
  • lib/src/ext/power_ext.dart (13 hints)
  • lib/src/ext/speed_ext.dart (13 hints)
  • lib/src/number/double.dart (13 hints)
  • lib/src/si/types/angle.dart (13 hints)
  • lib/src/si/types/time_instant.dart (13 hints)
  • lib/domain/electromagnetic.dart (12 hints)
  • lib/src/ext/area_ext.dart (12 hints)
  • lib/src/ext/pressure_ext.dart (12 hints)
  • lib/src/si/types/information.dart (12 hints)
  • lib/src/ext/time_ext.dart (11 hints)
  • lib/src/si/types/level.dart (9 hints)
  • lib/src/si/types/mass.dart (9 hints)
  • lib/src/si/types/temperature.dart (9 hints)
  • lib/src/si/types/temperature_interval.dart (9 hints)
  • lib/range/time_period.dart (8 hints)
  • lib/src/si/types/energy.dart (8 hints)
  • lib/src/si/types/information_rate.dart (8 hints)
  • lib/src/si/types/time.dart (8 hints)
  • lib/src/ext/charge_ext.dart (7 hints)
  • lib/src/ext/solid_angle_ext.dart (7 hints)
  • lib/src/si/types/area.dart (7 hints)
  • lib/src/si/types/length.dart (7 hints)
  • lib/domain/universal.dart (6 hints)
  • lib/src/ext/angular_momentum_ext.dart (6 hints)
  • lib/src/ext/force_ext.dart (6 hints)
  • lib/src/ext/temperature_ext.dart (6 hints)
  • lib/src/number/number.dart (6 hints)
  • lib/src/ext/entropy_ext.dart (5 hints)
  • lib/src/si/types/absorbed_dose.dart (5 hints)
  • lib/src/si/types/absorbed_dose_rate.dart (5 hints)
  • lib/src/si/types/activity.dart (5 hints)
  • lib/src/si/types/angular_acceleration.dart (5 hints)
  • lib/src/si/types/angular_speed.dart (5 hints)
  • lib/src/si/types/currency.dart (5 hints)
  • lib/src/si/types/dose_equivalent.dart (5 hints)
  • lib/src/si/types/exposure.dart (5 hints)
  • lib/src/si/types/permeability.dart (5 hints)
  • lib/src/si/types/pressure.dart (5 hints)
  • lib/src/si/types/scalar.dart (5 hints)
  • lib/src/si/types/speed.dart (5 hints)
  • lib/src/si/types/volume.dart (5 hints)
  • lib/number.dart (4 hints)
  • lib/src/ext/acceleration_ext.dart (4 hints)
  • lib/src/ext/magnetic_flux_ext.dart (4 hints)
  • lib/src/ext/mass_density_ext.dart (4 hints)
  • lib/src/ext/resistance_ext.dart (4 hints)
  • lib/src/si/types/acceleration.dart (4 hints)
  • lib/src/si/types/amount_of_substance.dart (4 hints)
  • lib/src/si/types/angular_momentum.dart (4 hints)
  • lib/src/si/types/capacitance.dart (4 hints)
  • lib/src/si/types/catalytic_activity.dart (4 hints)
  • lib/src/si/types/charge.dart (4 hints)
  • lib/src/si/types/charge_density.dart (4 hints)
  • lib/src/si/types/concentration.dart (4 hints)
  • lib/src/si/types/conductance.dart (4 hints)
  • lib/src/si/types/current.dart (4 hints)
  • lib/src/si/types/current_density.dart (4 hints)
  • lib/src/si/types/dynamic_viscosity.dart (4 hints)
  • lib/src/si/types/electric_field_strength.dart (4 hints)
  • lib/src/si/types/electric_flux_density.dart (4 hints)
  • lib/src/si/types/electric_potential_difference.dart (4 hints)
  • lib/src/si/types/energy_density.dart (4 hints)
  • lib/src/si/types/energy_flux.dart (4 hints)
  • lib/src/si/types/entropy.dart (4 hints)
  • lib/src/si/types/force.dart (4 hints)
  • lib/src/si/types/frequency.dart (4 hints)
  • lib/src/si/types/heat_flux_density.dart (4 hints)
  • lib/src/si/types/illuminance.dart (4 hints)
  • lib/src/si/types/inductance.dart (4 hints)
  • lib/src/si/types/kinematic_viscosity.dart (4 hints)
  • lib/src/si/types/luminance.dart (4 hints)
  • lib/src/si/types/luminous_flux.dart (4 hints)
  • lib/src/si/types/luminous_intensity.dart (4 hints)
  • lib/src/si/types/magnetic_field_strength.dart (4 hints)
  • lib/src/si/types/magnetic_flux.dart (4 hints)
  • lib/src/si/types/magnetic_flux_density.dart (4 hints)
  • lib/src/si/types/mass_density.dart (4 hints)
  • lib/src/si/types/mass_flow_rate.dart (4 hints)
  • lib/src/si/types/mass_flux_density.dart (4 hints)
  • lib/src/si/types/molar_energy.dart (4 hints)
  • lib/src/si/types/molar_entropy.dart (4 hints)
  • lib/src/si/types/permittivity.dart (4 hints)
  • lib/src/si/types/power.dart (4 hints)
  • lib/src/si/types/radiance.dart (4 hints)
  • lib/src/si/types/radiant_intensity.dart (4 hints)
  • lib/src/si/types/resistance.dart (4 hints)
  • lib/src/si/types/solid_angle.dart (4 hints)
  • lib/src/si/types/specific_energy.dart (4 hints)
  • lib/src/si/types/specific_heat_capacity.dart (4 hints)
  • lib/src/si/types/specific_volume.dart (4 hints)
  • lib/src/si/types/spectral_irradiance.dart (4 hints)
  • lib/src/si/types/surface_tension.dart (4 hints)
  • lib/src/si/types/thermal_conductivity.dart (4 hints)
  • lib/src/si/types/torque.dart (4 hints)
  • lib/src/si/types/volume_flow_rate.dart (4 hints)
  • lib/src/si/types/wave_number.dart (4 hints)
  • lib/src/si/units.dart (4 hints)
  • lib/src/ext/conductance_ext.dart (3 hints)
  • lib/src/ext/current_ext.dart (3 hints)
  • lib/src/ext/kinematic_viscosity_ext.dart (3 hints)
  • lib/src/ext/magnetic_flux_density_ext.dart (3 hints)
  • lib/range/quantity_range.dart (2 hints)
  • lib/src/ext/capacitance_ext.dart (2 hints)
  • lib/src/ext/electric_potential_difference_ext.dart (2 hints)
  • lib/src/ext/illuminance_ext.dart (2 hints)
  • lib/src/ext/permeability_ext.dart (2 hints)
  • lib/src/ext/permittivity_ext.dart (2 hints)
  • lib/src/ext/specific_energy_ext.dart (2 hints)
  • lib/src/ext/volume_flow_rate_ext.dart (2 hints)
  • lib/src/ext/angular_speed_ext.dart (1 hint)
  • lib/src/ext/energy_flux_ext.dart (1 hint)
  • lib/src/ext/inductance_ext.dart (1 hint)
  • lib/src/ext/spectral_irradiance_ext.dart (1 hint)
  • lib/src/si/exponential_units.dart (1 hint)
  • lib/src/si/misc_quantity.dart (1 hint)
  • lib/src/ext/amount_of_substance_ext.dart (Run dartfmt to format lib/src/ext/amount_of_substance_ext.dart.)
  • lib/src/number/fraction.dart (Run dartfmt to format lib/src/number/fraction.dart.)
  • lib/src/si/immutable_quantity_exception.dart (Run dartfmt to format lib/src/si/immutable_quantity_exception.dart.)
  • lib/src/si/number_format_si.dart (Run dartfmt to format lib/src/si/number_format_si.dart.)

Maintenance suggestions

The package description is too short. (-15 points)

Add more detail to the description field of pubspec.yaml. Use 60 to 180 characters to describe the package, what it does, and its target use case.

Maintain an example. (-10 points)

Create a short demo in the example/ directory to show how to use this package.

Common filename patterns include main.dart, example.dart, and quantity.dart. Packages with multiple examples should provide example/README.md.

For more information see the pub package layout conventions.

Dependencies

Package Constraint Resolved Available
Direct dependencies
Dart SDK >=1.24.3 <3.0.0
dart2_constant ^1.0.1+dart1 1.0.2+dart2
intl >=0.15.0 <2.0.0 0.16.1
logging ^0.11.3 0.11.4
Transitive dependencies
path 1.6.4
Dev dependencies
test >=0.12.30