Why need to call "priming lua_pcall()" before running function in Lua script

[Nan Xiao <xiaonan830818@...>]

Hi all,

After reading "Calling Lua From a C Program", I see it's need to call "priming lua_pcall()" or

"priming lua_dofilel()" before using "lua_getglobal()" to get a function and run it successfully.

Or the program will complain "attempt to call a nil value".

But after googling and going through "Programming in Lua", I can't find what is under the

hood. Could anyone can explain why need the the magical "priming lua_pcall"?

Thanks very much in advance!

Best Regards

Nan Xiao