[go-nuts] const interface

As the documentation for binary.Write says, the data must be a fixed-size
value. Ints are not fixed-size (int32s are), and the language rules mean
that the call passes c as an int-typed value (see
http://blog.golang.org/constants).

Nothing inconsistent here, although it is subtle.

-rob

Hi,

[email protected] writes:
No. The Spec [1] can shed some light on this. c is an untyped integer
constant. As such, it has a default type of int. In both your cases, it
will be given a type implicitely when used as an operand in an
expression. In the first case, the expression fixes the type to be
uint32, so it will be given this type *in this expression*. In the
second expression, it is passed as an interface{}, which has no explicit
type, so it reverts to its default type, which is int.

This is "consistent behaviour of an untyped constant", as defined by the spec
(which you accept by writing const c = 0xCAFE in the first
place. Without untyped constants and their definition, that would be an
error).
If you want a typed constant, just do const c = uint32(0xCAFE), then you
get "consistent behaviour with a typed constant" (which you might phrase
as just "constistent").

Best,

Axel

[1] http://golang.org/ref/spec#Constants