clearCache.Object: Clear fields that are defined to have cached values

In R.oo: R Object-Oriented Programming with or without References

Clear fields that are defined to have cached values

Description

Clear fields that are defined to have cached values by assigning NULL to these fields.

Usage

## S3 method for class 'Object'
clearCache(this, recursive=TRUE, gc=FALSE, ...)

Arguments

recursive	If TRUE, the same method is called also on all fields that are Object:s. Circular dependencies can exists.
gc	If TRUE, the garbage collector is called, otherwise not.
...	Not used.

Value

Returns itself (invisible).

Author(s)

Henrik Bengtsson

See Also

For more information see Object.

Examples

# - - - - - - - - - - - - - - - - - - - - - - - - - - - -
# Defining a class with a 'cached' fields
# - - - - - - - - - - - - - - - - - - - - - - - - - - - -
setConstructorS3("CachedObject", function(...) {
  extend(Object(), "CachedObject",
    ...
  )
})

setMethodS3("as.character", "CachedObject", function(this, ...) {
  s <- NextMethod("as.character", this, ...)
  s <- sprintf("%s RAM: %.2fkb.", s, objectSize(this)/1024)
  s
})


# - - - - - - - - - - - - - - - - - - - - - - - - - - - -
# Example of clearing a cache fields, reassigning it,
# and then clearing it again
# - - - - - - - - - - - - - - - - - - - - - - - - - - - -
obj <- CachedObject(a=1, b=1:10^5, "cached:c"=1:10^6)
print(obj)
print(ll(obj))

clearCache(obj, gc=TRUE)
print(obj)
print(ll(obj))


obj$c <- 1:10^6
print(obj)
print(ll(obj))

clearCache(obj, gc=TRUE)
print(obj)
print(ll(obj))


# - - - - - - - - - - - - - - - - - - - - - - - - - - - -
# Clearing cached fields recursively and make sure it
# avoids race conditions due to circular dependences
# - - - - - - - - - - - - - - - - - - - - - - - - - - - -
objA <- CachedObject(a=2, "cached:c"=1:10^6, prev=NULL)
print(ll(objA))

objB <- CachedObject(a=2, "cached:c"=1:10^6, prev=objA)
print(ll(objB))

objC <- CachedObject(a=3, "cached:c"=1:10^6, prev=objB)
print(ll(objC))

objA$prev <- objC

clearCache(objA, gc=TRUE)
print(ll(objA))
print(ll(objB))
print(ll(objC))

R.oo documentation built on Nov. 2, 2024, 1:07 a.m.