Lazy Evaluation in Bash

Question

Is there more elegant way of doing lazy evaluation than the following:

pattern=\'$x and $y\'
x=1
y=2
eval \"echo $pattern\"

results:

1 and 2         


        

Answer 1

One safe possibility is to use a function:

expand_pattern() {
    pattern="$x and $y"
}

That's all. Then use as follows:

x=1 y=1
expand_pattern
echo "$pattern"

You can even use x and y as environment variables (so that they are not set in the main scope):

x=1 y=1 expand_pattern
echo "$pattern"