Question

I have some Java code that uses curly braces in two ways

// Curly braces attached to an 'if' statement: if(node.getId() != null) {     node.getId().apply(this); }  // Curly braces by themselves: {     List<PExp> copy = new ArrayList<PExp>(node.getArgs());     for(PExp e : copy)     {         e.apply(this);     } } outAMethodExp(node); 

What do those stand-alone curly braces after the first if statement mean?

Answer 1

The only purpose of the extra braces is to provide scope-limit. The List<PExp> copy will only exist within those braces, and will have no scope outside of them.

If this is generated code, I assume the code-generator does this so it can insert some code (such as this) without having to worry about how many times it has inserted a List<PExp> copy and without having to worry about possibly renaming the variables if this snippet is inserted into the same method more than once.