tclVarFun: 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?

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?

Value

Most of these functions return a tclVar object.

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.

Examples

Run this code

## 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!)