Description Usage Arguments Value See Also Examples
A datamap is an object database for accessing and storing foreign objects.
newMap
creates the object based on the provided mapper type.
1 |
type |
Character vector length one describing the mapper to use. |
... |
Arguments to be passed to the mapper's |
An object of class codedatamap.
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 | newMapper(
type="EXAMPLE",
init=function(map,symbols=c('foo','bar','baz'),len=3){
# Install symbols that the users passes in from newMap().
lapply(symbols,install,map)
# Now let's add some state to the internal portion of our map.
map$len <- len
# Returning FALSE means failure
return(TRUE)
},
get = function(x) {
cat("I'll just get",x,"for you.\n")
# len is pulled from the internal portion of the map
# by lexical scoping rules. Anything can be returned here, but we
# default to a numeric value
rnorm(len)
},
assign = function(x,val){
cat("Calling assign",val,"to",x,".\n")
},
finalize = function(map){
cat("Finalization can clear any state, like shutting down database\n")
cat("connections, socket connections, etc.\n")
},
# The rest of the arguments are copied to the internal portion of the map.
foo = 'bar'
)
m <- newMap('EXAMPLE')
# Summary of the map
m
# [[ works
m[['bar']]
# datamaps are environments
with(m,bar)
# use functions to access either installed objects
# or those that aren't.
m$get('bar')
# adding extra variables to the map.
with(m,x <- 'buzzle')
m
# attach the map the search path
# and update either the map or the search path position.
# changes are persistent
mapAttach(m)
baz
rm(m)
foo
detach('datamap:EXAMPLE')
|
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