Parenthesize every raw list .
The precedence of the comma operator is so low that, even when it's in a list context, it may not act the way that a casual reader expects. For example, the following assignment:
@todo = 'Patent concept of 1 and 0', 'Sue Microsoft and IBM', 'Profit!';
is identical to:
@todo = 'Patent concept of 1 and 0'; 'Sue Microsoft and IBM'; 'Profit!';
That's because the precedence of the comma is less than that of assignment, so the previous example is really a set of "junior semicolons":
(@todo = 'Patent concept of 1 and 0'), 'Sue Microsoft and IBM', 'Profit!';
For that reason it's a good practice to ensure that comma-separated lists of values are always safely enclosed in parentheses, to boost the precedence of the comma-separators appropriately:
@todo = ('Patent concept of 1 and 0', 'Sue Microsoft and IBM', 'Profit!');
But be careful to avoid the all-too-common error of using square brackets instead of parentheses:
@todo = ['Patent concept of 1 and 0', 'Sue Microsoft and IBM', 'Profit!'];
This example produces a @todo array with only a single element, which is a reference to an anonymous array containing the three strings.