In AX7 X++ now supports the readonly keyword. Semantically it is identical to readonly in C#.
In short; it allows you to define members on a class that can only be initialized in the declaration and in the constructor.
public void new(str _identifier)
public void foo()
The big question is “when to use it?” In my opinion the actual use scenarios are limited – simply because other language constructs are still missing.
In X++ we still recommend the construct pattern and the newFrom pattern. These patterns recommend the new method to not have any parameters – readonly has little applicability, when the new method is parameter-less.
So why do we prefer parameter-less new methods?
- It enables serialization of classes using the pack/unpack pattern – all classes extending RunBase are subject to this.
- It enables the extension framework and smart customizations.
Once X++ supports getters/setters and method overloading (at least of the new method) – then readonly will become handy.
If you have a good use scenario for readonly – please share in the comments section below.
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