Thanks for the responses! No luck so far though:
julia> akeep = Ptr{Ptr{Void}}(0)
ERROR: type cannot be constructed
I changed the signature of the ccall to Ptr{Ptr{Void}}, but declaring
akeep=Ptr{Void} and passing &akeep yields: ERROR: `convert` has no method
matching convert(::Type{Ptr{None}}, ::Type{Ptr{None}})
Declaring akeep=Ptr{Ptr{Void}} and passing akeep directly yields: ERROR:
`convert` has no method matching convert(::Type{Ptr{Ptr{None}}},
::Type{Ptr{Ptr{None}}})
I don't understand what there is to convert. The two types mentioned in
either error message are the same...
Haven't tried 0.4 yet.
@tkelman, I'll be very happy to release this when/if I can make it work.
On Thursday, October 8, 2015 at 10:08:33 PM UTC-4, Isaiah wrote:
>
> akeep = Ptr{Void}
>
>
> This is declaring a "DataType" variable (try `typeof(Ptr)` to see what I
> mean). You need to construct an instance, so try: `akeep =
> Ptr{Ptr{Void}}(0)`
>
> Then the ccall signature should be `(Ptr{Ptr{Void}},)`.
>
> (see also:
> http://docs.julialang.org/en/release-0.3/manual/calling-c-and-fortran-code/#type-correspondences
> )
>
> On Thu, Oct 8, 2015 at 9:36 PM, Dominique Orban <[email protected]
> <javascript:>> wrote:
>
>> I'm trying to call the C interface to the HSL MA97 from Julia. It's a
>> symmetric indefinite factorization library that uses OpenMP. One of the
>> main C functions expects a void** as argument. The example that ships with
>> the library declares a void* variable named akeep. The main program doesn't
>> do anything with it except that it passes &akeep (i.e., a void**) to some
>> of the library functions. Presumably, those functions allocate memory
>> pointed to by akeep. It's a bit perplexing, but that's how it is. At the
>> end, there's a call of the form free(&akeep).
>>
>> My question is: what syntax should I use in Julia to perform the same
>> operations? Naively, I'm tempted to try something like
>>
>> akeep = Ptr{Void}
>> ccall((:some_function, "libwhatever"), Void, (Ptr{Void},), akeep)
>>
>> but that returns the error message: `convert` has no method matching
>> convert(::Type{Ptr{None}}, ::Type{Ptr{None}}).
>>
>> Replacing akeep with &akeep in the ccall returns: expected Ptr{None}, got
>> Type{Ptr{None}}.
>>
>> What might be the appropriate syntax here? And more importantly, is this
>> a recipe for a segfault?'
>>
>> This is with Julia 0.3.11.
>>
>> Thanks!
>>
>
>
