Quick Concatenation Question For Unpacking?
So I found that .. and , can work for concatenating for example,
1 | print("hello" .. " my dude") |
OR
1 | print("hello", " my dude") |
however, that's not my main question. vvvvv
1 | code = {5455, 45, 23, 65, 89, 21, 45} |
2 |
3 | print("this code ; " .. unpack(code)) |
this only prints the first number of the table, 5455
WHILE
1 | code = {5455, 45, 23, 65, 89, 21, 45} |
2 |
3 | print("this code ; ", unpack(code)) |
this print ALL of the numbers of the table. I don't understand. Can someone explain the logic behind this? I am confused and it will help me understand things better in the future.
1 answer
unpack turns a table into a tuple. Tuples can be used in three places in Lua:
(The end of) an assignment:
1 | local t = {1, 2} |
2 |
3 | local a, b = unpack(t) |
4 | -- same as a, b = 1, 2 |
(The last part of ) function calls:
1 | local t = {1, 2} |
2 |
3 | print(unpack(t)) |
4 | -- same as print(1, 2) |
and (the last element in) table literals:
1 | local t = {1, 2} |
2 |
3 | local u = {3, unpack(t)} |
4 | -- same as u = {3, 1, 2} |
If you use a tuple anywhere else, such as with an operator like + or .., it will only use the first value in the tuple:
1 | local t = {1, 2} |
2 | local a = 3 * unpack(t) |
3 | -- same as a = 3 * 1 |
Parenthesis also take only the first value in a tuple:
1 | local t = {1, 2} |
2 |
3 | print( (unpack(t)) ) |
4 | -- same as print(1) |
In your case, it's the .. which eliminates the remainder of the tuple after the first one.
print isn't really a way to "concatenate" strings, it's just something it happens to do if you give it multiple things.
You can use table.concat(list, " ") to concatenate the elements of list, separating them by spaces. (Note that this requires the elements of list be properly strings / numbers; unlike print, tostring will not be automatically called for other types of objects).
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