Question

I am starting to learn Lua from Programming in Lua (2nd edition) I didn’t understand the following in the book.

network = {
          {name ="grauna", IP="210.26.30.34"},
          {name ="araial", IP="210.26.30.23"},
}

If we want to sort the table by field name, the author mentions

table.sort(network, function (a,b) return (a.name > b.name) end }

Whats happening here? What does function (a,b) stand for? Is function a key word or something.

If was playing around with it and created a table order

 order={x=1,x=22,x=10} // not sure this is legal

and then did

 print (table.sort(order,function(a,b) return (a.x > b.x) end))

I did not get any output. Where am I going wrong?

Thanks

Answer 1

It’s an anonymous function that takes two arguments and returns true if the first argument is less than the second argument. table.sort() runs this function for each of the elements that need sorting and compares each element with the previous element.