Thanks. It's all working now.
On Friday, October 9, 2015 at 7:11:35 AM UTC-4, Tony Kelman wrote:
>
> On 0.3, try convert(Ptr{Ptr{Void}}, 0)
>
>
> On Friday, October 9, 2015 at 4:03:51 AM UTC-7, Dominique Orban wrote:
>>
>> 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]>
>>> 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!
>>>>
>>>
>>>
