At least for why is doesn't work, the eval runs in the scope of the current
module, not in the local scope of the function:
julia> myarg = "a string"
"a string"
julia> f(myarg::Int) = println(eval(:myarg))
f (generic function with 1 method)
julia> f(10)
a string
I don't know if there is a way to get the value associated with a symbol
inside a function.
On Sunday, February 8, 2015 at 8:45:55 PM UTC-5, Dominique Orban wrote:
>
> I'm writing a function that takes optional arguments. Many of them must be
> arrays of a certain size. I'd like to perform a quick check of their size
> at the top of the function and thought it would be a good use case for meta
> programming, but I can't seem to get the syntax right. Here's an example
> that hopefully illustrates what I'm trying to do:
>
> function test(a; x=zeros(5), y=zeros(5))
> for arg in {:x, :y}
> if length(eval(arg)) != 5 # ERROR: x not defined
> error(@eval $(string(arg, " must have length 5")))
> end
> end
> # ...
> end
>
> I tried *@eval $(arg)* in the argument to *length*, but without success.
> Line 3 always causes "ERROR: x not defined" to be raised.
>
> Thanks!
>
