## Create ``Alias'' (Pointer) to \R Object

## Usage

    new <- .Alias(expr)

## Arguments

`expr` | an R expression; typically a name.
`new` | new name by which `expr` can be accessed.

## Description

`.Alias` creates an alias to another (part of) an R object which is more (memory-) efficient than usual assignment.

## Value

an identical copy of `expr`.

## WARNING

This has a dangerous semantic, and consequences can be unexpected (it can be used to defeat the call-by-value illusion). Know what you are doing before using `.Alias`!

## References

~put references to the literature/web site here ~

## See Also

`<-` for usual assignments.

## Examples

    mop <- options()
    Op <- .Alias(mop)
    ## Any change to mop is reflected in Op and vice versa!
    mop $ newslot <- pi
     Op $ newslot # 3.1415..
    mop $ digits <- "Wow!"
     Op $ another <- 2
    mop $ another; Op $ digits
    all(names(mop) == names(Op))# TRUE -- Op and mop  *ARE* the same thing

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