*Need help creating my package!*
I am writing a program to perform a Monte-Carlo simulation of a plane's
normal vector in Julia. I want to publish my "Geometry" package for others
to use it... because it is awesome!
Please do not ask me why I would want run such a simulation. Also: please
don't ask why my code is so inelegant (using simple "Vector"s instead of
defining a "Coordinate" type). It is a secret. All I can say is that I
will make billions of dollars selling this to people in a parallel universe
where everybody is high... all the time.
I am following this thread because I see people having similar problems to
mine. But apparently, there are no issues reported by the developers of
the major Julia packages... so I am willing to accept I am doing something
wrong. I just want someone (anyone) to tell me what that is (I just can't
figure it out).
Here is part of my program:
#I'm running Monte-Carlo, so I need that awesome "Distributions" package:
using Distributions
#This is my awesome Geometry module that I want to distribute to others:
module Geometry
#I define a plane with 3 points... because using its normal is for
suckers:
type Plane
point1::Vector
point2::Vector
point3::Vector
end
#Then I waste the CPU's time computing the normal... 'cuz I'm awesome:
Normal2(x::Plane) = cross(x.point2-x.point1, x.point3-x.point1)
export Plane
export Normal2
end
#Of course, I want to use that module using Julia's great succinct syntax:
using Geometry
#Bet you can't guess why varying the z-coordinate will make me billions of
dollars!:
#That's why I am a genous:
function varyzdim(x::Vector, amount::Number)
result = copy(x)
result[3] *= 1+amount
return result
end
#Principal algorithm:
function simulate_monte_carlo(nruns::Integer)
plane = Plane(Float64[0,0,0], Float64[1,0,0], Float64[0,1,0])
n = Normal2(plane)
dist=Normal(0, .01)
return [varyzdim(n,x) for x=rand(dist, nruns)]
end
#Step 1: Run simulation
result = simulate_monte_carlo(3)
@show result
#Step 2: ...
#Step 3: Profit!
:Done
*Problems:*
- I was not able to call Geometry.Normal2 as Geometry.Normal... because
it collided with Distributions.Normal.
- I *could* define "Normal(x::Plane)" to "extend"
Distributions.Normal... but then my friend will not be able to use my
awesome module. Apparently, the universe where *he* is selling his
software will be destroyed by Schrödinger's cat if the code is not
deterministic. He tells me the cat will loose it or something... I don't
know... I don't think I really care as long as he is happy.
- In any case, I don't *want* to extend Distributions.Normal, because
Geometry.Normal is very much >>>orthogonal<<< to the former.
- I guess it would work if "Normal" was defined in Base... I mean
pretty much *everybody* will want to use Julia's Base module anyways....
But it's not really practical for me to fork Julia just to add method
"Normal" to module Base.
- If I decide to keep the method name as "Normal2"... how do I know no
other module out there won't try to use the same workaround as mine? Then
I will not be playing nice with *that* module (I am getting a little
anxious now...).
- I could write this in C++... But I don't think I have the patience
anymore (after getting hooked on Julia).
*So what am I missing here?*
1. Am I doing something wrong? What is it about Julia's module system
that I am not understanding.
2. Am I being too fussy? Is it unreasonable for me to expect that my
Monte-Carlo simulation can take advantage of multi-dispatch on *both*
"Geometry.Normal" and "Distributions.Normal" without needing to explicitly
import Normal from their respective modules?
3. Is this case not considered common enough to warrant improvements to
Julia's module/namespace system in the future? Should I accept that the
best solution in the long term is to only "import Geometry". Is the best
solution to explicitly qualify my version of Normal as "Geometry.Normal"
whenever two modules export the same symbol... despite having un-ambiguous
signatures (AFAIK)?
4. Am I wrong about not being able to extend Base? Is it in fact
possible for me to extend base in order to add the symbol "Normal" without
forking? ...But then what do I do about having broken the Distributions
module (because Base would then "own" Normal)?
*Please! I would appreciate the input of *anyone* who can help me make the
Geometry package work harmoniously with other packages (present & future)
in Julia's ecosystem.*
PS:
I could understand if a solution to this problem is non-trivial... I can
also understand if this is simply not a high priority for the core team
right now... But that's not the principal message I am getting from this
thread at the moment.
