You can still use meta-programming to generate the code
function removeLine(poly, index)
for op = (:a, :b, :x1, :y1, :x2, :y2, :typ)
@eval splice!($poly.$op, $index)
end
end
On Thursday, May 8, 2014 5:40:35 PM UTC+3, Stéphane Laurent wrote:
>
> Thank you Johan and Jameson.
>
> Johan, I don't know how to make a loop on the fields with a function. For
> example this doesn't work:
>
> function removeLine(poly::Poly, index::Int)
>
> for op = (:a, :b, :x1, :y1, :x2, :y2, :typ)
>
> splice!(poly.$op, index)
>
> end
>
> end
>
>
> How to do, please ?
>
>
> Le jeudi 8 mai 2014 15:59:06 UTC+2, Jameson a écrit :
>>
>> Replace your macro with a function and delete the uses of eval. You code
>> will be faster, and easier to understand. Most of the difficulty people
>> seem to have with macros comes from thinking they are a type of function
>> call -- the @ character is supposed to remind you that this is not true.
>>
>> On Thursday, May 8, 2014, Johan Sigfrids <[email protected]> wrote:
>>
>>> I myself have been hitting my head against the wall that is
>>> meta-programming in Julia. I think I can answer your first question at
>>> least.
>>>
>>> Q1: This is because the line poly = emptyPoly doesn't create a new copy
>>> of a ploygon but a reference to the empty one so that both poly and
>>> emptyPoly
>>> refer to the same data. You need to do poly = deepcopy(emptyPoly) .
>>>
>>> On Thursday, May 8, 2014 9:56:27 AM UTC+3, Stéphane Laurent wrote:
>>>
>>> Hello everybody,
>>>
>>> Below I define two new types : Line and Poly. The Poly type is intended
>>> for stacking some lines.
>>>
>>> type Line
>>>
>>> a::Float64 # intercept
>>>
>>> b::BigFloat # slope
>>>
>>> x1::BigFloat # x-coordinate of first vertex
>>>
>>> y1::BigFloat # y-coordinate of first vertex
>>>
>>> x2::BigFloat # x-coordinate of second vertex
>>>
>>> y2::BigFloat # y-coordinate of second vertex
>>>
>>> typ::Bool # type of the line (true:upper, false:lower)
>>>
>>> end
>>>
>>>
>>> type Poly
>>>
>>> a::Vector{Float64}
>>>
>>> b::Vector{BigFloat}
>>>
>>> x1::Vector{BigFloat}
>>>
>>> y1::Vector{BigFloat}
>>>
>>> x2::Vector{BigFloat}
>>>
>>> y2::Vector{BigFloat}
>>>
>>> typ::Vector{Bool}
>>>
>>> end
>>>
>>>
>>>
>>> I also define the empty Poly:
>>>
>>> emptyPoly = Poly(Array(Float64,0), Array
>>>
>>>
