Источник:
http://sysdictcoder.com/blog/detecting-default-values/
==============
So I haven’t posted in a long time. I finally fixed some technical issues on the blog and upgraded to a recent version of Wordpress. Let’s start with a quick tip to warm up :)
As you know X++ supports methods with default values. In Ax it’s possible to detect when such a default value was used at runtime with
prmIsDefault(). To see this for yourself, create a class with a method like this:
void someMethod
(int i
= 1) { ;
if (prmIsDefault(i
)) { info
('Default');
} else { info
('Value given');
} }
And call it from another method.
o.
someMethod(); o.
someMethod(1);
Even though the value is the same in both cases a different info message will be displayed.
Now you may be wondering how this can be useful. Some scenarios:
- Avoiding expensive operations if the default value was used
- Avoiding unwanted initializations
- Dealing with customizations that require extra parameters in standard Ax classes
If you do a search for prmIsDefault() in the AOT you will see it’s used often. Classes with the Ax prefix are the most obvious example. Because getters and setters are rolled into a single method it’s necessary to know if the method was used as a getter or a setter and keep track of modified fields.
Источник:
http://sysdictcoder.com/blog/detecting-default-values/