Simple way to dynamically replace placeholder with value at Groovy strings - string

Question

I'm trying to find laconic and efficient way to replace placeholders with values at the Groovy Strings. But I can't find convenient solution for 2 cases:
When String with the placeholder and the value are defined at different classes.
When the String is passed as argument to a method, and should be replaced with local's variable value. Here is the illustration of 2 approaches I have tried:
class A {
static def strPlaceHolder = 'token = ${tokenValue}';
static def strRefPlaceHolder = "token = ${->tokenRef}";
}
class B {
def tokenRef = "token reference as field";
void parseGString(GString str) {
println str; //fails here. No property tokenRef for class: A. Though I've expected that "this" is B
}
void parseString(String str) {
def tokenValue = "token value as local variable";
println str; //I know why it doesn't work as required. But how to make something similar
}
}
new B().parseString(A.strPlaceHolder); //token = ${tokenValue}
new B().parseGString(A.strRefPlaceHolder); //fails,

Answer 1

You could replace your GString fields with closures and pass those closures to your methods. e.g.:
class A {
static def strPlaceHolder = { token -> "token = ${token}" }
}
class B {
def tokenRef = "token reference as field";
void parseGString(def closure) {
println closure(tokenRef)
}
void parseString(def closure) {
def tokenValue = "token value as local variable"
println closure(tokenValue)
}
}
new B().parseString(A.strPlaceHolder);
new B().parseGString(A.strPlaceHolder);