Embedding the Lua Shell

Table of contents

• Lua Shell As A Replacement For The IOC Shell
• Common Lua Environments

Lua Shell As A Replacement For The IOC Shell

The Lua shell can be called as a C function, which allows it to be used on vxWorks or as a replacement for the IOC shell in a soft IOC. The same parameters apply as when calling the command inside the IOC shell. A main.cpp file might look like:

#include "luaShell.h"

int main(int argc,char *argv[])
{
    if(argc>=2) {
        luash(argv[1]);
        epicsThreadSleep(.2);
    }
    luash(NULL);
    epicsExit(0);
    return(0);
}

Common Lua Environments

In the above code, there are two different Lua shell calls. One to read in a given script, and one to provide an interactive shell. As the code stands, any objects that are created in the input script aren’t available to the interactive shell. Say, for example, you have a library that provides useful functions that are used in scripts, you would have to include that library again once you are in the interactive shell, and there wouldn’t be a way to automate that.

Therefore, there is a way to define that you want different calls to luash to use a common environment. The luashSetCommonState command is included in the luaShell.h file and sets a default environment that subsequent luash calls will use. The command takes a C string; if the string matches the name of a state created using luaNamedState(), it will use that state, otherwise it will create a new state with that name. So the above code changed to allow the interactive shell to reference code from the interpreted script would look like:

#include "luaShell.h"

int main(int argc,char *argv[])
{
    luashSetCommonState("default");

    if(argc>=2) {
        luash(argv[1]);
        epicsThreadSleep(.2);
    }
    luash(NULL);
    epicsExit(0);
    return(0);
}