Merge pull request #1 from PMunch/master

Add an example on how to use it

examples/loader.nim

@@ -0,0 +1,51 @@
+# Compile with: nim c --passL:-rdynamic -r loader.nim
+import os
+import dynlib
+import libffi
+when defined(linux):
+  proc dlerror(): cstring {.importc.}
+else:
+  proc dlerror(): string = "Unknown error"
+
+echo "Trying to load the library at: " & $(getAppDir() / "libplugin.so")
+# First let's load a library to find procedures in
+var dll = loadLib($(getAppDir() / "libplugin.so"), false)
+if dll == nil:
+  echo "Something went wrong with loading the plugin:\n" & $dlerror()
+  quit 1
+
+# Now let's try and get a symbol from it
+var procSym = dll.symAddr("hello")
+
+# We need to set up our call first. This procedure takes one int argument
+var
+  cif: Tcif
+  params: ParamList
+# The argument the procedure takes
+params[0] = type_sint64.addr
+# Prepare the call, with the aforementioned params, and no return type
+if OK != prep_cif(cif, DEFAULT_ABI, 1, type_void.addr, params):
+  echo "Something went wrong with preparing the statement"
+  quit 1
+
+# Now let's set up a list of arguments
+var args: ArgList
+var i = 100
+args[0] = i.addr
+
+# And call the symbol with our argument
+call(cif, procSym, nil, args)
+
+# Let's do another one. This time without arguments, but with a return type
+if OK != prep_cif(cif, DEFAULT_ABI, 0, type_sint64.addr, params):
+  echo "Something went wrong with preparing the statement"
+  quit 1
+
+# Again load the symbol
+var highFiveSym = dll.symAddr("highFive")
+
+# Set up the position of our return value and call the procedure
+var theFive = 0
+call(cif, highFiveSym, theFive.addr, args)
+echo theFive
+

examples/plugin.nim

@@ -0,0 +1,7 @@
+# Compile with: nim c --noMain --app:lib plugin.nim
+proc hello(x: int) {.exportc.} =
+  echo "Hello world, ", x
+
+proc highFive(): int {.exportc.} =
+  result = 5
+  echo "Here you go!"