>
> That is, I'm solving a set of N polynomial equations, where N is a
> parameter.
>
That sounds interesting, could you post some more details? At this stage,
it's not clear if you really need to generate a new program at all. But if
you do want to do that, then for sure, building the AST will be easier and
more reliable than generating text.
Best,
Cédric
On Saturday, December 26, 2015 at 3:24:51 PM UTC-5, Stuart Brorson wrote:
>
> Cool. Thanks for the code example. I will play with it to see what I
> can do with it.
>
> Thanks,
>
> Stuart
>
>
> On Sat, 26 Dec 2015, Josh Langsfeld wrote:
>
> > As Yichao is hinting, you may find a macro to be a cleaner way of making
> > your functions instead of constructing and parsing a string.
> >
> > macro return_fcn(N)
> > xexprs = Expr[:($(symbol(:x,i)) = X[$i]) for i=1:N]
> > return esc(:(
> > function $(symbol(:f,N))(X::Vector)
> > $(xexprs...)
> > mu = X[$(N+1)]
> > end
> > ))
> > end
> >
> > julia> macroexpand(:(@return_fcn(2)))
> > :(function f2(X::Vector)
> > x1 = X[1]
> > x2 = X[2]
> > mu = X[3]
> > end)
> >
> > julia> macroexpand(:(@return_fcn(4)))
> > :(function f4(X::Vector)
> > x1 = X[1]
> > x2 = X[2]
> > x3 = X[3]
> > x4 = X[4]
> > mu = X[5]
> > end)
> >
> >
> >
> > On Saturday, December 26, 2015 at 2:03:56 PM UTC-5, Stuart Brorson
> wrote:
> >>
> >> Julia users,
> >>
> >> I'm fiddling around with Julia's strings & metaprogramming. I am
> >> constructing a function by concatenating a bunch of strings together
> >> to create my function, like this:
> >>
> >> function return_fcn(N)
> >> P = string("function f$N(X::Vector)\n")
> >> for i in 1:N
> >> P = string(P, "x$i = X[$i];\n");
> >> end
> >> P = string(P, "mu = X[$(N+1)];\n")
> >> etc....
> >>
> >> When I execute this code, I get:
> >>
> >> julia> y = return_fcn(2)
> >> "function f2(X::Vector)\nx1 = X[1];\nx2 = X[2];\nmu = X[3];\n"
> >>
> >> However, what I really want to see is
> >>
> >> function f2(X::Vector)
> >> x1 = X[1];
> >> x2 = X[2];
> >> mu = X[3];
> >>
> >> "show(y)" doesn't seem to do what I want. Later, when I do
> >>
> >> eval(parse(y))
> >>
> >> then I get a function which executes correctly. My problem is simply
> >> that I can't get Julia to give me a string I can read easily. This
> >> will be a very big issue for me when N -> 1024, 2048, etc....
> >>
> >> Questions:
> >>
> >> 1. How can I escape the \n to get a real <CR><LF> in my displayed
> >> string?
> >>
> >> 2. Is this the optimal way to construct a program for later execution
> >> (i.e. metaprogramming)?
> >>
> >> Thanks for all wisdom you have to offer.
> >>
> >> Stuart
> >>
> >
>
