printf wrapping/tabbing on spaces in variables

If you need to print the contents of variables that happen to contain spaces via printf you would typically code as follows:

#!/bin/bash
export var_01='This is variable 01'
export var_02='continuing in variable 02'
printf '%-30s %-30s\n' $var_01 $var_02 >> temp.txt

However, this will output as follows:

This                           is                            
variable                       01                            
continuing                     in                            
variable                       02   

Instead of the expected:

This is variable 01            continuing in variable 02   

To prevent this, enclose the variables in double quotes:

#!/bin/bash
export var_01='This is variable 01'
export var_02='continuing in variable 02'
printf '%-30s %-30s\n' "$var_01" "$var_02" >> temp.txt