Access this / vm instance from props default (VueJS)

Question

I have a plugin that sets some variables to vue's object prototype.

I need to access these variables from a prop's default property. How can I achieve this?

Using the following example, webpack throws some undefined error.

//...
props: {
    size: {
        type: String,
        required: false,
        default: this.$myPlugin.size
    }
}

Answer 1

For Vue 2, you can specify the default as a function that returns the default value. That should have access to the current instance as this.

props: {
    size: {
        type: String,
        required: false,
        default () {
            return this.$myPlugin.size
        } 
    }
}

The relevant line in the Vue source code is here if you're curious. Note that the function is explicitly called with vm as its this value.