Type UVError in base

musm · November 1, 2016, 10:29pm

JuliaLang/julia/blob/01e256310227b859651f4622d5c7c68b742ed25d/base/libuv.jl#L57


      
          
          
# A dict of all libuv handles that are being waited on somewhere in the system
          # and should thus not be garbage collected
          const uvhandles = ObjectIdDict()
          preserve_handle(x) = uvhandles[x] = get(uvhandles,x,0)::Int+1
          preserve_handle_new(x) = uvhandles[x] = 1
          unpreserve_handle(x) = (v = uvhandles[x]::Int; v == 1 ? pop!(uvhandles,x) : (uvhandles[x] = v-1); nothing)
          
          
## Libuv error handling ##
          
          
type UVError <: Exception
              prefix::AbstractString
              code::Int32
              UVError(p::AbstractString,code::Integer)=new(p,code)
          end
          
          
struverror(err::Int32) = unsafe_string(ccall(:uv_strerror,Cstring,(Int32,),err))
          struverror(err::UVError) = struverror(err.code)
          uverrorname(err::Int32) = unsafe_string(ccall(:uv_err_name,Cstring,(Int32,),err))
          uverrorname(err::UVError) = uverrorname(err.code)

This looks a bit troublesome.
Why is the inner constructor needed?
The inner constructor also is ::Integer however code only accepts Int32.
I’m led to believe these are bugs.

StefanKarpinski · November 1, 2016, 10:39pm

The real question is why do we have this type at all? We shouldn’t be surfacing details of the library we use for I/O to the user.

musm · November 1, 2016, 10:45pm

I think it’s primarily used for internal handling of errors with libuv. The type UVError is not exported.

yuyichao · November 1, 2016, 10:45pm

This is not a bug. It will not error if you pass in a Int64.

musm · November 1, 2016, 10:50pm

The code::Int32 in the UVError type will actually do a convert? My understanding was it was more of an assertion.

yuyichao · November 1, 2016, 11:25pm

The ::Int32 here is not an assertion. It’s a declaration of slot type much like local a::Int32 or Vector{Int32}. When assigning to such a location, there’s an implicit conversion and type assertion.

I believe these are documented in the types doc (search for convert in the page).