Named functions

[Sikwan]

Hi !

I am using lupa to validate some LUA expressions persisted to a data store from a python webapp. The thing is my expressions contains some custom functions defined elsewhere. I am wondering is there is a way to define them before running the expression I am trying to validate ?

EG:

expr = "field('brand') == 'audi'"

Here field is a custom function, I am just trying to enforce that the LUA syntax is valid, not execute exactly the whole function so I figured I had to do something like that :

lua = LuaRuntime(unpack_returned_tuples=True)
lua.eval('function field(x) return x end')
print lua.eval(expr)

But I keep having this error :

Traceback (most recent call last):
  File "test-lua.py", line 8, in <module>
    lua.eval('function field((x) return x end')
  File "_lupa.pyx", line 168, in lupa._lupa.LuaRuntime.eval (lupa/_lupa.c:3399)
  File "_lupa.pyx", line 950, in lupa._lupa.run_lua (lupa/_lupa.c:13350)
lupa._lupa.LuaSyntaxError: error loading code: [string "<python>"]:1: '(' expected near 'field'

Am I doing something wrong or is this just not possible ?

Thanks a lot

[fried]

Hey use lua.execute() lua.eval() is the same except it places a return statement in front of your expression

[scoder]

As you can see from the traceback, your actual code duplicates the opening "(" in the function. Thus the error. lua.eval() works fine for defining functions (or any expression, really). It prepends the code with "return ", as fried said. execute() is for running arbitrary code that is not an expression.

[scoder]

If you really want named functions, you can write

func = lua.execute('function test(x) return x end; return test')

[Sikwan]

Works like a charm thanks a lot. I thought we couldn't reuse what was in "execute" in the same runtime, not sure why.

Thanks for the answer and the amazing work !

Cheers