I want to create a type, and need more flexibility than Julia's `type`
definitions offer (see <https://github.com/eschnett/FastArrays.jl>).
Currently, I have a function that generates the type, and returns the type.
I would like to make this a generated function (as it was in Julia 0.4).
The advantage is that this leads to type stability: The generated type only
depends on the types of the arguments pass to the function, and Julia would
be able to infer the type.
In practice, this looks like
using FastArrays
# A (10x10) fixed-size arraytypealias Arr2d_10x10 FastArray(1:10, 1:10)
a2 = Arr2d_10x10{Float64}(:,:)
In principle I'd like to write `FastArray{1:10, 1:10}` (with curly braces),
but Julia doesn't offer sufficient flexibility for this. Hence I use a
regular function.
To generate the type in the function I need to call `eval`. (Yes, I'm aware
that the function might be called multiple times, and I'm handling this.)
Do you have a suggestion for a different solution?
-erik
On Wed, Aug 10, 2016 at 11:51 AM, Jameson <vtjn...@gmail.com> wrote:
> It is tracking the dynamic scope of the code generator, it doesn't care
> about what code you emit. The generator function must not cause any
> side-effects and must be entirely computed from the types of the inputs and
> not other global state. Over time, these conditions are likely to be more
> accurately enforced, as needed to make various optimizations reliable
> and/or correct.
>
>
>
> On Wednesday, August 10, 2016 at 10:48:31 AM UTC-4, Erik Schnetter wrote:
>>
>> I'm encountering the error "eval cannot be used in a generated function"
>> in Julia 0.5 for code that is working in Julia 0.4. My question is -- what
>> exactly is now disallowed? For example, if a generated function `f` calls
>> another (non-generated) function `g`, can `g` then call `eval`? Does the
>> word "in" here refer to the code that is generated by the generated
>> function, or does it refer to the dynamical scope of the code generation
>> state of the generated function?
>>
>> To avoid the error I have to redesign my code, and I'd like to know ahead
>> of time what to avoid. A Google search only turned up the C file within
>> Julia that emits the respective error message, as well as the Travis build
>> log for my package.
>>
>> -erik
>>
>> --
>> Erik Schnetter <schnet...@gmail.com> http://www.perimeterinstitute.
>> ca/personal/eschnetter/
>>
>
--
Erik Schnetter <schnet...@gmail.com>
http://www.perimeterinstitute.ca/personal/eschnetter/
