A function to make available list elements inside a function or method

Inside a function, a call to spread() will attach to the function environment, sys.frame(), the elements in the list, or of the conversion to list of the object (e.g. named vector or FLPar), so that they be called by name. The function environment will be deleted once the function returns, so those variables won't make it to the environment from which the function was called, or further up in the call stack.

Usage

spread(object, FORCE = FALSE)

Arguments

object: A named list or vector whose elements are to be loaded into the calling environment.
FORCE: Should existing variable with matching names be redefined?

Value

Invisibly the names of the variables loaded into the calling environment.

Details

By default, spread() will not overwrite variables in the function environment with the same name as any list element, unless FORCE=TRUE

Author

The FLR Team

Examples


# EXAMPLE function
foo <- function (params) {
  a <- spread(params)
 print(a)
 x*y
}
# x and y are accesible to the internal calculation
foo(params=list(x=3.5, y=9))
#> [1] "x" "y"
#> [1] 31.5

# Works with FLPar
foo(params=FLPar(x=3L, y=0.99238))
#> [1] "x" "y"
#> [1] 2.97714

# Elements in object must be named
if (FALSE) foo(list(3, y=0.99238)) # \dontrun{}

# If a variable is missing from the spread object, function will fail
if (FALSE) foo(list(x=4)) # \dontrun{}
# Unless the variable is already defined in the calling environment,
# in this case <environment: R_GlobalEnv>
y <- 45
foo(params=list(x=4))
#> [1] "x"
#> [1] 180