Evaluating expressions

I am looking for a way to prevent 3 1-evaluation of a string containing variable names and 2- then evaluating these variable names inside a function 1 Can easily be achieved through single quotes but I am stumbling on step 2 The idea is myFunction(' This is a formatting string containing variables that are out of scope like $var1'); Inside the function var1 exists and I would like to have something like: myFunction($formatstring) { $var1=" I am in SCOPE"; print(eval($formatString)); } And all that would return This is a formatting string containing variables that are out of scope like I am in SCOPE