How to use Fiddle to call .dylib

[Liz Huang]

Hi,

I used DL to call intel fortran .dylib file successfully before, but DL is removed from
latest Ruby version. I tried to use fiddle and got error message "unknown symbol
'samplesize'", could anyone help to see where I did wrong? Thanks!

Liz

my fortran function is below (our_int is compatible with long in C, our_double is compatible with
double in C):

integer(our_int) function samplesize( maxn, delta, conf, errmsg ) result( answer )
!DEC$ ATTRIBUTES DLLEXPORT :: samplesize
!
! OUTPUT
! N: sample size
!
! EXAMPLE
! samplesize4(3000, .2, .90);
!

implicit none

integer(our_int), intent(in) :: maxn
real(our_dble), intent(in) :: delta, conf
character(len=err_msg_width), intent(out) :: errmsg

....

and I used DL to  call it like this before:

  require 'dl'
  require 'pathname'
     sspath = Pathname.new( "#{RAILS_ROOT}/lib/libsamplesize.dylib" )
      ss = DL.dlopen( sspath )
      samplesize = ss[ "samplesize_", "iiddS" ]
      session[:errmsg] = "                                                                                ";
      session[:n], args = samplesize[ session[:nmax], session[:delta],
                          session[:conf], session[:errmsg] ]

Now I tried to use fiddle as below:

    require 'fiddle'
      libm = Fiddle.dlopen( "/Library/WebServer/smart/lib/libsamplesize.dylib" )
#      samplesize = ss[ "samplesize_", "iiddS" ]
      samplesize=Fiddle::Function.new(libm['samplesize'],[Fiddle::TYPE_LONG,Fiddle::TYPE_DOUBLE,Fiddle::TYPE_DOUBLE,Fiddle::TYPE_VOIDP],Fiddle::TYPE_LONG)
      session[:errmsg] = "                                                                                ";
#      session[:n], args = samplesize[ session[:nmax], session[:sigma_sq],
#                          session[:delta], session[:conf], session[:errmsg] ]
      session[:n] = samplesize.call( session[:nmax], session[:delta],
                          session[:conf], session[:errmsg] )

but I got error:

unknown symbol "samplesize"

Extracted source (around line #34):

32 33 34 35 36 37

libm = Fiddle.dlopen( "/Library/WebServer/smart/lib/libsamplesize.dylib" ) # samplesize = ss[ "samplesize_", "iiddS" ] samplesize=Fiddle::Function.new(libm['samplesize'],[Fiddle::TYPE_LONG,Fiddle::TYPE_DOUBLE,Fiddle::TYPE_DOUBLE,Fiddle::TYPE_VOIDP],Fiddle::TYPE_LONG) session[:errmsg] = " "; # session[:n], args = samplesize[ session[:nmax], session[:sigma_sq], # session[:delta], session[:conf], session[:errmsg] ]

Rails.root: /Library/WebServer/smart

Application Trace | Framework Trace | Full Trace

app/controllers/samplesize_controller.rb:34:in `[]'
app/controllers/samplesize_controller.rb:34:in `compute'

[Liz Huang]

It seems not many people using Ruby to call Fortran .dylib, anyway, I figured that I need to wrap Fortran
with C...