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optimator999
optimator999
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Yielding is not allowed within a C or metamethod call

Apr 27, 2012 5:32 PM

The way I'm developing my plug in is that I'm creating individual modules, testing those modules and then integrating the modules into my plugin. The individual modules work. However, I have a problem when I try to integrate.

 

I'm using an anonymous function to call a function when a user presses a button. That function calls another lua file (is that a module?) If I place the require statement at the top of the file I receive the Yielding is not allowed within a C or metamethod call error.

 

However, if I place the require statement within the function that specifically requires accessing the lua file then I don't receive the error. Clearly, I don't understand what's going on. Can anyone explain what is happening here?

 

Thanks!

569 Views   5 Replies   Latest reply: optimator999, Apr 27, 2012 10:10 PM
 
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  • Rob Cole
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    1. Rob Cole,
    Apr 27, 2012 7:16 PM   in reply to optimator999
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    Does your module have executable code in the body of it? If so, consider putting it in a function, then call the function when you are ready, so nothing gets executed when the module is "require'd".

     
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  • Rob Cole
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    2. Rob Cole,
    Apr 27, 2012 8:50 PM   in reply to optimator999
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    try:

     

    action = function( button )

         -- start task

    end

     

    instead of:

     

    action = "call a function that starts a task"

     

    In the first case, you are assigning a function value to action which will get called when the user clicks the button.

    In the second case, you are calling a function and assigning the return value to action.

     

    eh?

     

    R

     
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  • optimator999
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    3. optimator999,
    Apr 27, 2012 9:31 PM   in reply to Rob Cole
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    Hey Rob,

     

    Thanks for helping me with this. Since this is so new to me, I'm all over the place and I'm having trouble even understanding what my problems are :-)

     

    Anyway, here's where I'm at:

     

    I have a button in sectionsForTopOfDialog. I have changed the action to be action = function() .... end

     

    When I press the button the function is called. The problem is when I call the LrHttp.post function. That's when the yield error is being thrown.

     
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  • John R. Ellis
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    4. John R. Ellis,
    Apr 27, 2012 9:49 PM   in reply to optimator999
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    The problem is when I call the LrHttp.post function. That's when the yield error is being thrown.

    The error message "Yielding is not allowed within a C or metamethod call" arises when you call a function or method that needs to be invoked from a task created by LrTasks or LrFunctionContext.postAsyncTaskWithContext.

     

    In this case, the LrHttp functions have to be called from a task.  The SDK documentation is pretty good (but not perfect) about calling out which functions and methods have to be called from a task. 

     
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  • optimator999
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    5. optimator999,
    Apr 27, 2012 10:10 PM   in reply to John R. Ellis
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    Thanks! Of course, that was my problem.

     
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