Water 5-Common Data Types-Generic Object and Collection

Contract
Return type	wob
Parameter key	Default value	Type
key	req
lookup	false	boolean
returns	"first"	string
if_missing	"return"	string
default	false	boolean

Water Contract
<method get key =req lookup =false=boolean returns ="first" if_missing="return" default =false/>

Get provides a way to access values of fields via a method call. Most of the time you access a field you can do simply:

<class boat color="blue"/>
boat.color

"blue"

If the field name is in a variable and you want it to be dynamically computed, you can do something like:

boat.<get "co".<join "lor"/>/>

"blue"

which is equivalent to:

boat.<get "color"/>

"blue"

Note that all the arguments to get are of execution kind ekind.code . Normally, get looks for the field only in the subject and if it doesn't find it in the subject, it returns false . But you can have get do a lookup into the parents of the subject by supplying an argument of lookup=true like so:

boat.<get "color" lookup=true/>

"blue"

in which case the parent of boat , and its parent will also be searched. The closest parent to the subject that has the passed in field key will supply the value of the call to get . The above call to get behaves just like: boat.color The default value of the lookup argument is false . Th _subject to get defaults to the local environment:

<set aaa=333>  
   <get "aaa"/>  
  </>

a wob
Parameter key Default value Type
if_missing "return" string
If the key can not be found, return this value.

<thing/>.<get "x" if_missing=0/>

<thing/>.<get "x" if_missing=error/>

error

a wob

if_missing=false

The default value. If the key can not be found, it returns false.

a wob

if_missing=error

An error is thrown rather than returning a value.

If you want to get a vector of ALL the values of a particular field in all the ancestors, call get with returns="all" like so:

<<thing color="red"/> color="white"/>.
     <get "color" returns="all"/>

<vector "white"/>

Here we are creating a parent object with a color of "red" and a child object of that parent with a color of white. The returned vector is <vector "white" "red"/> where the order of the elements is the "closest value to _subject is first", in this case "white" . If you use returns="all" and lookup="false" then you will get a vector of one value, the value of the field in _subject