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Last data update: 2014.03.03

R: Manipulate R variables and functions from tcl and back

tclVarFun

R Documentation

Manipulate R variables and functions from tcl and back

Description

These functions are intended to provide a better "duality" between the name of variables in both R and tcl, including for function calls. It is possible to define a variable with the same name in R and tcl (the content is identical, but copied and coerced in the two respective environments). It is also possible to get the value of a tcl variable from R, and to call a R function from within tcl. These functionnalities are provided in the tcltk package, but Tcl variable usually have different internal names as R equivalents.

Usage

makeTclNames(names, unique = FALSE)
tclFun(f, name = deparse(substitute(f)))
tclGetValue(name)
tclSetValue(name, value)
tclVarExists(name)
tclVarFind(pattern)
tclVarName(name, init = "", keep.existing = TRUE)

Arguments

`names`	transform names so that they are valid for variables in Tcl.
`unique`	should these names be unique in the vector?
`f`	an R function. currently, do no support functions with arguments.
`name`	the name of a variable.
`value`	The value to place in a variable.
`pattern`	a pattern to search for.
`init`	initial value to use when creating the variable.
`keep.existing`	if the tcl variable already exist, should we keep its content?

Details

These functions are similar to tclVar() from package tcltk, except for the following change: here, it is possible to propose a name for the created tcl variable, or to set or retrieve the content of a tcl variable that is not mirrored in R.

Value

Most of these functions return a tclVar object.

Author(s)

Philippe Grosjean

Examples

## Not run: 
## These cannot be run by examples() but should be OK when pasted
## into an interactive R session with the tcltk package loaded

## Tcl functions and variables manipulation
tclVarExists("tcl_version")
tclVarExists("probably_non_existant")
tclVarFind("tcl*")

## Using tclVarName() and tclGetValue()...
## intented for better match between R and Tcl variables
Test <- tclVarName("Test", "this is a test!")
## Now 'Test' exist both in R and in Tcl... In R, you need to use
tclvalue(Test) # to retrieve its content
## If a variable already exists in Tcl, its content is preserved using
## keep.existing = TRUE
	
## Create a variable in Tcl and assign "just a test..." to it
tclSetValue("A_Variable", "just to test...")
## Create the dual variable with same name
A_Variable <- tclVarName("A_Variable", "something else?")
tclvalue(A_Variable) # Content of the variable is not changed!

## If you want to retrieve the content of a Tcl variable,
## but do not want to create a reference to it in R, use:
    
## Create a Tcl variable, not visible from R
tclSetValue("Another_Variable", 1:5)
tclGetValue("Another_Variable") # Get its content in R (no conversion!)
tclSetValue("Another_Variable", paste("Am I", c("happy", "sad"), "?"))
tclGetValue("Another_Variable") # Get its content in R (no conversion!)

## End(Not run)