Ah, well that was perhaps a bad example. My understanding was the
you could interpolate an interable. Consider then the horner macro
macro horner(x, p...)
ex = esc(p[end])
for i = length(p)-1:-1:1
ex = :($(esc(p[i])) + t * $ex)
end
Expr(:block, :(t = $(esc(x))), ex)
end
if I have a vector of constant coefficients, shouldn't I be able to splice
them into the macro call?
julia> c = [1.:5]
5-element Array{Float64,1}:
1.0
2.0
3.0
4.0
5.0
julia> @horner(.x, c...)
ERROR: syntax: invalid identifier name "."
On Friday, August 29, 2014 8:45:00 PM UTC-7, Jameson wrote:
>
> that would be utterly pointless, since you can already just write:
> @mymacro(“aaa”, “bbb”, “ccc”)
>
> if you are intending to look at values, you should be using a function. a
> macro is a function but it's also special in that it takes the quoted AST
> of it’s arguments during parsing, not their values during runtime
>
> observe when b... is getting printed:
>
> julia> macro mymacro(a,b)
> println(b)
> end
>
> julia> f() = @mymacro(a,b...)
> b...
> f (generic function with 1 method)
>
> julia> f()
>
>
>
>
> On Fri, Aug 29, 2014 at 9:45 PM, Don MacMillen <[email protected]
> <javascript:>> wrote:
>
>> I meant something like this
>>
>> julia> macro mymacro(a,b,c)
>> println(c)
>> end
>>
>> julia> @mymacro("aaa", ("bbb", "ccc")...)
>> ERROR: wrong number of arguments
>>
>> which works fine for functions
>>
>> julia> function myfunc(a,b,c)
>> println(c)
>> end
>> myfunc (generic function with 1 method)
>>
>> julia> myfunc("aaa", ("bbb", "ccc")...)
>> ccc
>>
>>
>>
>>
>> On Friday, August 29, 2014 6:02:45 PM UTC-7, Jameson wrote:
>>
>>> splicing into a macro works for me:
>>>
>>> julia> macro mymacro(a,b)
>>> println(b)
>>> end
>>>
>>> julia> @mymacro(x, y...)
>>> y...
>>>
>>>
>>>
>>>
>>> On Fri, Aug 29, 2014 at 8:57 PM, Don MacMillen <[email protected]>
>>> wrote:
>>>
>>>> The slides are great. Many thanks for sharing.
>>>>
>>>> I do have a question about macros that maybe you can answer. In your
>>>> nb on
>>>> metaprogramming you have the horner macro listed and it uses a temporary
>>>> variable t. But this macro can be written without using a temporary
>>>> variable.
>>>> It turns out to be slower (the no temp version) if we are computing a
>>>> bunch of
>>>> polynomials with the same coefficients, but is a tiny bit faster if the
>>>> coefficients
>>>> are always changing. So are the Expr's cached? Or is something else
>>>> going on?
>>>>
>>>> Also (OK I have two questions) it looks like we cannot splice into a
>>>> macro call?
>>>> Ie @mymacro(x, y...) doesn't work?
>>>>
>>>> Thanks again.
>>>>
>>>> Don
>>>>
>>>>
>>>> On Friday, August 29, 2014 4:08:44 AM UTC-7, Steven G. Johnson wrote:
>>>>>
>>>>> I just gave a talk on Julia at EuroSciPy, and managed to escape
>>>>> alive. :-)
>>>>>
>>>>> I think they will post a video at some point, but in the meantime the
>>>>> slides and IJulia notebooks are posted at:
>>>>>
>>>>> https://github.com/stevengj/Julia-EuroSciPy14
>>>>>
>>>>> --SGJ
>>>>>
>>>>
>>>
>
