nwsIFetchTry-methods: Iterate Through Values of a netWorkSpace Variable
In nws: R functions for NetWorkSpaces and Sleigh

Description Usage Arguments Details See Also Examples

Create a function that acts as a destructive iterator over the values of the specified variable.

1 2	## S4 method for signature 'netWorkSpace' nwsIFetchTry(.Object, xName, defaultVal=NULL)

`.Object`	a netWorkSpace class object.
`xName`	character string specifying name of the variable to be fetched.
`defaultVal`	value to return, if xName is not found in the netWorkSpace.

The iterator function returned by the nwsIFetchTry method takes no arguments, and works just like the nwsFetchTry method, specified with the same arguments that were passed to nwsIFetchTry method. Note that the nwsIFind and nwsIFindTry methods are much more useful, since they provide the only way to iterate over values of a variable non-destructively. The nwsIFetch and nwsIFetchTry methods are provided for completeness.

nwsFetchTry, nwsIFetch

## Not run: 
ws <- netWorkSpace('nws example')
nwsStore(ws, 'x', 10)
it <- nwsIFetchTry(ws, 'x', NA)
it()  # returns the value 10
it()  # returns NA

## End(Not run)