May 2018
Beginner
252 pages
6h 19m
English
Sometimes, you need to find out whether a certain object has a certain field (or function). The find phrase returns true if the field exists, none if it doesn't:
find person1 'tel ;== truefind person1 'id-number ;== none
Again, you have to use the ' literal word syntax. Once you know the field exists, access its value with the familiar path notation, such as person1/tel ;== "333-4271". However, you could also use select with the same notation:
select person1 'tel ;== "333-4271"select person1 'id-number ;== none
Some reflective words exist to get the contents, the list of fields, or the list of the values of an object, as shown in the following snippet:
person1: object [ name: "Mueller" tel: "333-4271" ]body-of ...