It's not obvious. Try this:
macro mytest(fn::Symbol, ex::Expr)
qex = Expr(:quote, ex) # here's the magic incantation
quote
$(esc(fn))($qex)
end
end
Works for symbols that you want to keep as symbols, too.
But your `foo` method is not defined for an expression, so your test case will
throw an error.
--Tim
On Sunday, August 03, 2014 11:46:43 AM Abe Schneider wrote:
> I found one previous conversation related to this, but unfortunately the
> answer didn't work for me. Hopefully I'm not asking an obvious question.
>
> Suppose I have some macro:
> macro mytest(fn::Symbol, ex::Expr)
> quote
> $(esc(fn))($ex)
> end
> end
>
> and I have some function that takes in the expression to operate on it:
> myfun(ex::Expr) = ...
>
> the problem (which may be obvious) is that `$ex` gets evaluated with the
> macro, and I won't pass an `Expr` to `myfun`. A quick demonstration:
>
> foo(x, y) = x+y
> println(expandmacro(:(@mytest foo 1+2)))
>
> gives:
> begin # .../mtestmod.jl, line 38:
> foo(mtestmod.+(1,2))
> end
>
> What I can't figure out is how to keep `ex` an expression that is passed to
> foo (at least without writing out Expr by hand). I've tried many
> combinations of syntax to try to preserve the Expr-ness of `ex`.
>
> Thanks!
