Hi, just a quick question on the scope/environment of an expression.
I am using the Expr construct inside a function to create an expression,
and I would then want to use this expression in various different places.
Here's a short example
First we have a simple function "funky" that takes in a function "ff", and
applies it to two symbolic arguments :x and :y
julia> function funky(ff::Function)
Expr(:call, ff, :x, :y)
end
funky (generic function with 1 method)
We define x and y to be 1 and 2 respectively
julia> x,y = 1,2
(1,2)
No surprise here, when funky is passed with the function "+", it adds x and
y together
julia> eval(funky(+))
3
However, now I want to use this expression with different bindings for x
and y, I attempt the following
julia> function funfun(x, y)
eval(funky(+))
end
funfun (generic function with 1 method)
Which doesn't seem to work. Here the result is sitll 3, presumably it is
using the earlier bindings of x=1, y=2
julia> funfun(4,5)
3
I would really liked the last result to be 9.
So far it seems the expression uses static scoping and it's looking up the
binding for :x and :y in the frame generated by calling "funky", and not
finding it there, it looks up :x and :y in the
global frame, which is 1 and 2.
Is there a way to bind the symbols in an expression to different things? is
there like an "environment" dictionary where we can mess with, or is there
some clean way of doing it?
Much much much appreciated!!!
--evan
