HasValidConstructor

Summary

Severity - Fail

Check method - Here

Details

The HasValidConstructor check ensures that any BHoM object which implements a constructor with parameters contains all of the parameters it requires to satisfy the Serialisation requirement.

Constructors should only exist on objects implementing the IImmutable interface. Objects with this interface should have properties which are get only (no set accessor). All of these get only properties should be parameters to the constructor, with the parameter name matching the property name following the usual lowercase conventions for parameter names.

Consider the following IImmutable object, which does not have a constructor.

public class MyObject : BHoMObject, IImmutable
{
    public virtual int MyInt { get; }
    public virtual string MyString { get; }
    public virtual Point MyPoint { get; set; }
}

This object will not correctly deserialise, as it will not be able to adequately set the properties MyInt and MyString. Therefore, a constructor must be provided with the parameter names matching, so the deserialisation can correctly align the deserialised data to the object property.

The property MyPoint does not have to be a parameter to the constructor, as it implements a set accessor. This is true for any property, including those inherited from the base BHoMObject.

As such, a valid constructor would look like this:

public MyObject(int myInt, string myString)
{
    //Constructor logic
}

Example of a valid object

The entire class, in its valid form, would look like this:

public class MyObject : BHoMObject, IImmutable
{
    public virtual int MyInt { get; }
    public virtual string MyString { get; }
    public virtual Point MyPoint { get; set; }

    public MyObject(int myInt, string myString)
    {
        //Constructor logic
    }
}

Example of an invalid object

If the constructor does not contain input parameters for all of the properties which implement only the get accessor, this will flag as a failure under this check. The following object is therefore incompliant, as only MyInt has a matching input parameter:

public class MyObject : BHoMObject, IImmutable
{
    public virtual int MyInt { get; }
    public virtual string MyString { get; }
    public virtual Point MyPoint { get; set; }

    public MyObject(int myInt)
    {
        //Constructor logic
    }
}

More information

More information on the use of IImmutable interface within the BHoM can be found here.