Constraining Dart’s Numeric Types And Why You May Want To Do This

Constraining Dart’s Numeric Types And Why You May Want To Do This
7 min read

Do you want to understand constraining dart’s numeric types and why you are required to do this? If yes, then go through this guide and gather all the essential details about such a process now.

In general, there are a wide range of languages that are useful for development work and among that, many people prefer using Dart. The Ada language is the most extraordinarily typed language and it has the simplest yet powerful feature. Many best flutter developers from flutter agency have used it and have gained a wide range of benefits.

The subtype in the Ada is the type together with the associated constraint. It is the subset of values of the existing type. For instance,

subtype Small_Int is Integer range -10 .. 10;

It declares the type named Small_Int that is the integer subtype with the same operation as the integer. But it is constrained to the value range of around -10 to 10.

Trying anything to assign the value to the type that is outside the constraint range can cause the Ada runtime to raise the constraint error that could never be ignored, instead it can only be handled. Such type can be used to best reflect certain values to be stored. It can also give you wide range of benefits such as:

  • Better error checking possibilities
  • Simple to prove the program properties with various restricted types
  • Person who read the code can have the clear understanding of the variable purpose

A best example of this is nothing but converting the data from the outside world into certain types in the application. It is nothing but deserializing the byte stream from the socket into the record type or structure.

The subtype will never allow any value outside the constraints to be set, either anywhere in the application or at the point of deserialization. It is very essential in safety or high integrity critical systems, where the propagation of the invalid value into application may have some negative consequences.

Now here you may have doubts that you can do such a task in Dart. Of course it is possible. But you could not implement it at the runtime as similar to the Ada.

This Dart is very much flexible with the combination of the operator overloading and class extension that you can model the working subtyping framework. Here in this article, only certain ints can be considered. But the code can be made very generic.

At first, you are required to create the abstract subtype class so that you can derive the wide range of the concrete type.

Here you can get the chance to set the constraints for certain subtypes and use the private method boundsCheck to go through the constraints. The ArgumentError can be raised when the check fails. After that, you can check out the + operator and equality operator.

For certain equality, you can check out some comparisons to the ints and other subtypes which are similar for the addition of ints and other types derived from the subtype.

Here you must note that the return type of a certain addition operator can be dynamic to enable the default operation for the derived types. Now you can use it in certain effective ways. The main way is to create the general purpose subtype and use the type aliasing for aiding readability.

It can let you write the subtyped integers.

The addition now will simply become as:

numEggs1 += numEggs2;

Here you can know that the subtype constraint could never be violated. Other required operators can also similarly add. Till this, everything will be fine and further the implementation can also allow this:

numEggs += numPeas;

It is mainly since; both the types can be derived from the subtype. It doesn’t naturally read and it is probably not what you are expecting.

Further they can tighten this by adding the strict type checking mechanism and while they are at it they check that variable could never be used unless it can be initialized. Therefore, the addition operation can become the most essential process of the Dart.

Then the addition of the peas in the pod to eggs in the box mentioned above can now throw as certain types AScore and ADozen when instantiated with a strict typing flag.

Although it can be derived still from the subtype that can now be treated as the different type. Here type aliasing doesn’t require to be used. There is nothing that can directly stop the user creating the EggsInABox type from the subtype.

Building the fleshed-out production-ready subtyping mechanism with the equivalent unit test suite will only suit some since it is not trivial. But when it is implemented, it can be re-used in many of the applications and packages.

Here the code is not the real take out, instilling the questioning mindset in the reader’s eyes. When you are looking at the code differently and ask certain questions, then you are on the way to produce more type safe code when compared to the standard Dart allows.

Impact of Dart apps:

Generally, the Dart app regularly targets a wide range of platforms. For instance, the flutter app may target the android, iOS and the web. Here the code can be very much similar to the app which isn’t based on the platform specific libraries or uses certain numbers in the way that are platform dependent. Find here various dart tips and tricks for flutter developers.

Dart always has allowed the platform specific representations and certain semantics for certain numbers, for reasons of code size, platform interoperability and performance. The Dart code can be run on both web and native platforms for years and certain number implementation differences are rarely the problem. The type code behaves the same here.


From the above mentioned scenario, now you have got the idea about constraining dart’s numeric types and why you are required to do this. So why are you still waiting? Now you can hire dedicated front end developers and then proceed further with this process. These experienced developers can help you a lot.

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Ruben Gray 167
Hello, I am Ruben Grey, a seasoned Flutter developer with over 10+ years of experience and a consultant for Flutter Agency USA, where I help develop innovative...
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