samples/trycatch_test.mlua

-------------------------------------------------------------------------------
-- Copyright (c) 2006-2013 Fabien Fleutot and others.
--
-- All rights reserved.
--
-- This program and the accompanying materials are made available
-- under the terms of the Eclipse Public License v1.0 which
-- accompanies this distribution, and is available at
-- http://www.eclipse.org/legal/epl-v10.html
--
-- This program and the accompanying materials are also made available
-- under the terms of the MIT public license which accompanies this
-- distribution, and is available at http://www.lua.org/license.html
--
-- Contributors:
--     Fabien Fleutot - API and implementation
--
-------------------------------------------------------------------------------

-{ extension 'trycatch' }


----------------------------------------------------------------------
print "1) no error"
try
   print("   Hi")
end


----------------------------------------------------------------------
print "2) caught error"
try
   error "some_error"
catch x then
   printf("   Successfully caught %q", x)
end


-- [[
----------------------------------------------------------------------
print "3) no error, with a finally"
try
   print "   Hi"
finally
   print "   Finally OK"
end


----------------------------------------------------------------------
print "4) error, with a finally"
try
   print "   Hi"
   error "bang"
catch "bang"/{_} then
   print "   Bang caught"
finally
   print "   Finally OK"
end


----------------------------------------------------------------------
print "5) nested catchers"
try
   try
      error "some_error"
   catch "some_other_error" then
      assert (false, "mismatch, this must not happen")
   end
   catch "some_error"/{x} then
   printf("   Successfully caught %q across a try that didn't catch", x)
catch x then
   assert (false, "We shouldn't reach this catch-all")
end


----------------------------------------------------------------------
print "6) nested catchers, with a 'finally in the inner one"
try
   try
      error "some_error"
   catch "some_other_error" then
      assert (false, "mismatch, this must not happen")
   finally
      print "   Leaving the inner try-catch"
   end
catch "some_error"/{x} then
   printf("   Successfully caught %q across a try that didn't catch", x)
catch x then
   assert (false, "We shouldn't reach this catch-all")
end


----------------------------------------------------------------------
print "7) 'finally' intercepts a return from a function"
function f()
   try
      print "   into f:"
      return "F_RESULT"
      assert (false, "I'll never go there")
   catch _ then
      assert (false, "No exception should be thrown")
   finally
      print "   I do the finally before leaving f()"
   end
end
local fr = f()
printf("   f returned %q", fr)


----------------------------------------------------------------------
print "8) don't be fooled by nested functions"
function f()
   try
      local function g() return "from g" end
      printf("   g() returns %q", g())
      return "from f"
   catch _ then
      assert (false, "No exception should be thrown")
   end
end
local fr = f()
printf("   f returned %q", fr)

----------------------------------------------------------------------
print "*) done."