types.Function.tostring

Returns a string that names the type and identity of the closure.

Return value

A string shaped like (function : 0x...). Both a script closure and a native closure print the same function tag; nothing in the string tells them apart. The address is the closure's own identity, not its body: cloning a closure or binding it to a new environment produces a different address.

Notes

Takes no arguments; f.tostring(1) throws wrong number of parameters passed to native closure 'tostring' (2 passed, 1 required).

Because the address changes from run to run, code must never compare or print tostring() of a closure for anything other than a human to eyeball while debugging.

Example

function f() {}
let s = f.tostring()
println("s.slice(0, 11) =", s.slice(0, 11)) // "(function :" - the address itself is not stable
println("typeof s =", typeof s)
try { f.tostring(1) } catch(e) { println("f.tostring(1) throws:", e) }

s.slice(0, 11) = (function :
typeof s = string
f.tostring(1) throws: wrong number of parameters passed to native closure 'tostring' (2 passed, 1 required)

See also