 |
lua-l archive |
|
|
||
|
On 13/07/2017 14:54, Nathaniel Musgrove wrote:
On Thu, Jul 13, 2017 at 5:47 AM, Luiz Henrique de Figueiredo <lhf@tecgraf.puc-rio.br> wrote:Allowing t to be omitted is confusing because it is in the interest of the programmer to be explicit about what metatable is being set. setmetatable(v) is not explicit and seems very confusing to me.There are exactly zero other scenarios in Lua where f(nil) produces different behavior than f(). The fact that this function is the sole exception to the rule violates the principle of least astonishment. If the programmer wishes to use an explicit nil, that should be their choice, not an arbitrary requirement that exists nowhere else. Regards, Nathaniel
I don't agree, sorry.Usually when you omit an argument and that argument it's interpreted as nil it is a strong hint that that argument is intended to be optional and some *senisble* default is to be used.
in setmetatable the t argument is not at all optional, semantically, it is the very "target" of the operation. It would be very confusing to be able to omit an argument just as a shortcut for `nil`, when you just want to change the metatable of `nil`. This goes *against* the principle of least astonishment, IMO: if I'm setting a new metatable (something very low level and "risky"), I like to be explicit. What's the point of having t default to "nil". Note that here `nil` doesn't mean "no argument", but it means `nil` really, i.e. the type `nil` whose only value is `nil`.
cheers! -- Lorenzo