Lua table syntax

Question

This seems to be legitimate Lua syntax:

example = { ["dummy"] = "foobar"}

Why would you use the above and not simply:

example = { dummy = "foobar"}

They appear to functionally the same...

It was surprising for me that I can't write, for example, t = { in=0, out=1, err=2 } — Egor Skriptunoff
– Egor Skriptunoff, Commented Nov 18, 2016 at 22:58
Surprising that you can't write? @egorskriptunoff it looks valid to me — warspyking
– warspyking, Commented Nov 19, 2016 at 13:39
@warspyking in is a keyword, so it can't be used as a table field name without brackets. — Colonel Thirty Two
– Colonel Thirty Two, Commented Nov 19, 2016 at 16:36

lhf · Accepted Answer · 2016-11-18 22:25:58Z

1

Because field names do not have to be identifiers: they can be any string, including strings having spaces, for instance.

The second statement is valid Lua syntax and is very convenient for field names that are identifiers.

Table keys do not have to be strings: they can actually be any value (except nil) and the [expr]=expr syntax for table entries allows the values of arbitrary expressions to be used as keys.

edited Nov 18, 2016 at 22:25

answered Nov 18, 2016 at 22:10

lhf

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2 Comments

warspyking Over a year ago

Can they be any value except nil? I'm pretty sure there's another one.

Egor Skriptunoff Over a year ago

except nil and nan.

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