mobservable minutia

test.js

// So these are essentially equivalent in the latest/upcoming mobservable release, yeah? (Not count differences from Babel)

class FormField {
  constructor() {
    makeReactiveProps( this, {
       pristine: "", 
       validators: [],
       value: "",
       isDirty() {
         return this.value != this.pristine
       },
       isValid() {
         return this.validators.every( validate => validate( this ) )
       }
    })
  }
}

// And 
class FormField {
  @observable pristine = ""
  @observable validators = []
  @observable value = ""
  
  @observable
  isDirty() {
    return this.value != this.pristine
  }
  
  @observable
  isValid() {
    return this.validators.every( validate => validate( this ) )
  }
}

// Correction, it'd be more like this:
class FormField {
  @observable pristine = ""
  @observable validators = []
  @observable value = ""
  
  @observable
  get isDirty() {
    return this.value != this.pristine
  }
  
  @observable
  get isValid() {
    return this.validators.every( validate => validate( this ) )
  }
}