NLua handling C# Exceptions

Question

I'm looking at NLua for scripting of an existing C# application, where C# functions called from lua may throw exceptions.

So far, I found this:

If the lua code does not handle an exception in a called C# function, NLua wraps and re-throws it so it can be handled at C# level.
If lua code does "catch" an exception via xpcall, I have found no way to access the exception's details (e.g -.Message)

The former allows me to get a debug.traceback(), a lua-level stackdump, but I don't get details of the exception. The latter provides the exception, but no way to get a Lua stackdump (I get lua file and line in .Source, but that isn't enough).

The question is:

Can I get details of a C# exception in a NLua "xpcall" error handler (? At least the .Message field, even better the actual exception type.
Alternatively, can I handle a C# exception in NLua (with the intention of creating a lua stackdump) and re-throw it?
Or can I get a lua stackdump somehow from the "lua state" when e.g.luaState.DoFile("myScript.lua") causes an exception?

Any help would be appreciated. NLua seems near-perfect for what I have in mind, if I could only sort out the exception handling.

score 3 · Accepted Answer · edited Apr 20 '16 at 07:06

3

You need to use pcall from your script. The NLua will wrap the exception and return on second value returned by pcall.

error, exception = pcall (someFunction)

if (not error) then
    print(exception.Message)
end

Example on GitHub.

edited Apr 20 '16 at 07:06

Uwe Keim

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answered Sep 01 '15 at 20:19

Vinicius Jarina

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Thanks, this works. So Lua's (x)pcall returns userdata as "exception", and "exception.InnerException.Message" is the .Message field thrown from the C# code. Neat. – xc6lx45 Sep 02 '15 at 16:30

NLua handling C# Exceptions

1 Answers1