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How to make a function parameter null by default?
I see two design choices for such a case, where a function parameter is optional: Make it a pointer and make it NULL by default: void foo (int i, std::vector * optional = NULL) { if (optional == NULL) { optional = new std::vector (); // fill vector with data } // process vector }
How to set default values of nullable properties?
The same approach is used by text-controls (e.g. in ASP.NET) where the Text property never returns null but String.Empty.
How to set default values for optional input?
If you declare default value, you dont have to specify type since it is type of assigned value and property is optional by default. This is the case of bar and foo properties. Alternatively you can use ? to mark that this property is optional but you cant declare its default value. This is the case of baz property.
How to set a default entity property value?
If you want to set a default entity property value, then you can initialize the entity field using the default value. For instance, you can set the default createdOn entity attribute to the current time, like this:
Do you have to make the parameter optional in an interface?
You don’t have to make the parameter optional in the implementation. Your code will make somewhat more sense then: This way, it’s unambiguous what the default value is. In fact, I’m pretty sure the default value in the implementation will have no effect, since the interface provides a default for it.
How to implemenit interface with different method parameters?
The classes implemenitng an interface must match the method signiture of the interface exactly including number and order of parameters. It also may throw only those checked Exceptions that are decalred in the throws clause of the interface method declaration.
How are optional parameters defined in JavaScript?
If optional parameters are defined on the interface, default value would be passed based on what is declared in the interface. One issue is that there is nothing stopping you from setting different optional values on the definition.