This module implements the ability to access symbols from shared libraries. On POSIX this uses the dlsym mechanism, on Windows LoadLibrary.

Examples

Loading a simple C function

The following example demonstrates loading a function called 'greet' from a library that is determined at runtime based upon a language choice. If the library fails to load or the function 'greet' is not found, it quits with a failure error code.

import dynlib

type
  greetFunction = proc(): cstring {.gcsafe, stdcall.}

let lang = stdin.readLine()

let lib = case lang
of "french":
  loadLib("french.dll")
else:
  loadLib("english.dll")

if lib == nil:
  echo "Error loading library"
  quit(QuitFailure)

let greet = cast[greetFunction](lib.symAddr("greet"))

if greet == nil:
  echo "Error loading 'greet' function from library"
  quit(QuitFailure)

let greeting = greet()

echo greeting

unloadLib(lib)