Castle Windsor - Null constructor argument

Question

How can I pass a null constuctor argument using Castle Windsor? I thought the following would work

<parameters>
  <repository>null</repository>
  <message>null</message>
</parameters>`

Deutschland

Answer 1

If you want them to be null, it means that they are non-essential dependencies. By having them as ctor arguments you suggest otherwise. You should redesign your class to have another constructor that takes only essential dependencies, if you wish that they not change throughout the lifetime of an object (be readonly), or expose them as properties.

With Windsor you can't make it to pass nulls, for reasons mentioned in the other answer.

Bokbokhara

Answer 2

Wouldn't it better to simply have an additional public constructor that doesn't take these parameters, then you wouldn't need to register the parameters in the config?

Affair

Answer 3

This was discussed a while back on the mail list, and at the time I looked into the code. Null values are deliberately filtered out (mainly because the complicate type resolution).

I couldn't find a simple way to make a special case to add them.

Ballenger

I think the reason is actually that constructor arguments are mandatory dependencies, so null makes no sense there. – Jaala