error loading module 's2sa.models' ... ambiguous syntax (function call x new statement)

[ili3p]

I get this error when running the model:

 ...allations/torch/install/share/lua/5.1/trepl/init.lua:384: error loading module 's2sa.models' from file './s2sa/models.lua':
        ./s2sa/models.lua:85: ambiguous syntax (function call x new statement) near '('
stack traceback:
        [C]: in function 'error'
        ...allations/torch/install/share/lua/5.1/trepl/init.lua:384: in function 'require'
        train.lua:6: in main chunk
        [C]: in function 'dofile'
        .../torch/install/lib/luarocks/rocks/trepl/scm-1/bin/th:145: in main chunk
        [C]: ?

The line in question is:

   x = nn.JoinTable(2):usePrealloc("dec_inputfeed_join",
                                             {{opt.max_batch_l, opt.word_vec_size},{opt.max_batch_l, opt.rnn_size}})
                                ({x, inputs[1+offset]}) -- batch_size x (word_vec_size + rnn_size)

And the same issue is present in a couple of places in s2sa.models. The issue is usePrealloc returns self and then we call again a function on this returned self. Changing this to:

 x = nn.JoinTable(2):usePrealloc("dec_inputfeed_join",{{opt.max_batch_l, opt.word_vec_size},{opt.max_batch_l, opt.rnn_size}})
x = x({x, inputs[1+offset]}) -- batch_size x (word_vec_size + rnn_size)

creates other issues later on.

[ili3p]

The issue is only present in Lua 5.1 and it is there to prevent likely bugs from function calls that spread across lines, like in the case above. The fix is to remove the new line characters and make the function calls one line. http://lua.2524044.n2.nabble.com/Ambiguous-syntax-td7644848.html#d1355301287000-706

I have to say, I agree with Lua 5.1. The code in s2sa/models.lua is very hard to understand.

[yoonkim]

We plan on refactoring/cleaning up the code soon. Please bear with us in the meanwhile :)