Lupa - Python中调用Lua

Lupa将LuaJIT集成到了Python模块中，可以在Python中执行Lua代码。比较有意思，也许以后用的着，记录一下。

基本用法：

>>> import lupa
>>> from lupa import LuaRuntime
>>> lua = LuaRuntime()

>>> lua.eval('1+1')
2

>>> lua_func = lua.eval('function(f, n) return f(n) end')

>>> def py_add1(n): return n+1
>>> lua_func(py_add1, 2)
3

>>> lua.eval('python.eval(" 2 ** 2 ")') == 4
True
>>> lua.eval('python.builtins.str(4)') == '4'
True

Lua中的Python对象

>>> lua_func = lua.eval('function(obj) return obj["get"] end')
>>> d = {'get' : 'got'}

>>> value = lua_func(d)
>>> value == 'got'
True

>>> dict_get = lua_func( lupa.as_attrgetter(d) )
>>> dict_get('get') == 'got'
True

>>> lua_func = lua.eval(
... 'function(obj) return python.as_attrgetter(obj)["get"] end')
>>> dict_get = lua_func(d)
>>> dict_get('get') == 'got'
True

Lua中的迭代循环：

>>> lua_copy = lua.eval('''
...     function(L)
...         local t, i = {}, 1
...         for item in python.iter(L) do
...             t[i] = item
...             i = i + 1
...         end
...         return t
...     end
... ''')

>>> table = lua_copy([1,2,3,4])
>>> len(table)
4
>>> table[1]   # Lua indexing
1

Lua中的Table：

>>> table = lua.eval('{10,20,30,40}')
>>> table[1]
10
>>> table[4]
40
>>> list(table)
[1, 2, 3, 4]
>>> list(table.values())
[10, 20, 30, 40]
>>> len(table)
4

>>> mapping = lua.eval('{ [1] = -1 }')
>>> list(mapping)
[1]

>>> mapping = lua.eval('{ [20] = -20; [3] = -3 }')
>>> mapping[20]
-20
>>> mapping[3]
-3
>>> sorted(mapping.values())
[-20, -3]
>>> sorted(mapping.items())
[(3, -3), (20, -20)]

>>> mapping[-3] = 3 # -3 used as key, not index!
>>> mapping[-3]
3
>>> sorted(mapping)
[-3, 3, 20]
>>> sorted(mapping.items())
[(-3, 3), (3, -3), (20, -20)]

（等等……）