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How to call specific Python functions from QT GUI

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  • JonBJ JonB

    @lfreeman6490
    No, you did not state that. You stated that the error message was the same. When it was not. Which I then have to deal with....

    Please state error messages correctly.

    Let's start with: what OS are you on?

    L Offline
    L Offline
    lfreeman6490
    wrote on last edited by
    #11
    This post is deleted!
    JonBJ 1 Reply Last reply
    0
    • JonBJ JonB

      @lfreeman6490
      No, you did not state that. You stated that the error message was the same. When it was not. Which I then have to deal with....

      Please state error messages correctly.

      Let's start with: what OS are you on?

      L Offline
      L Offline
      lfreeman6490
      wrote on last edited by
      #12

      @JonB I'm on windows 10
      Python 2.7, 32 bit
      QTCreator 3.0.1

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      • L lfreeman6490

        This post is deleted!

        JonBJ Offline
        JonBJ Offline
        JonB
        wrote on last edited by JonB
        #13

        @lfreeman6490 said in How to call specific Python functions from QT GUI:

        Either way, it is the same error

        No, it is not. It has different text, which I need if I am able to help you. Up to you whether you want help, but I'm not going to spend time when someone says an error is the same when it is different. You might know what's on your screen, I do not.

        After you made the change to the .pro file, did you re-run qmake?

        L 1 Reply Last reply
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        • JonBJ JonB

          @lfreeman6490 said in How to call specific Python functions from QT GUI:

          Either way, it is the same error

          No, it is not. It has different text, which I need if I am able to help you. Up to you whether you want help, but I'm not going to spend time when someone says an error is the same when it is different. You might know what's on your screen, I do not.

          After you made the change to the .pro file, did you re-run qmake?

          L Offline
          L Offline
          lfreeman6490
          wrote on last edited by
          #14

          @JonB Yes I did run QMake, it's now telling me

          LNK1104: cannot open file 'python27_d.lib'
          
          JonBJ 1 Reply Last reply
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          • L lfreeman6490

            @JonB Yes I did run QMake, it's now telling me

            LNK1104: cannot open file 'python27_d.lib'
            
            JonBJ Offline
            JonBJ Offline
            JonB
            wrote on last edited by JonB
            #15

            @lfreeman6490
            So when you ran qmake the include error went away?

            You are now in the link situation I described. You'd better tell the linker, via the .pro file, where to look for the python27_d.lib it is seeking from your LIBS += -lpython2.7 .... (Though I don't think from the error mesaage it can come from your LIBS += -lpython2.7.)

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            • JonBJ JonB

              @lfreeman6490
              So when you ran qmake the include error went away?

              You are now in the link situation I described. You'd better tell the linker, via the .pro file, where to look for the python27_d.lib it is seeking from your LIBS += -lpython2.7 .... (Though I don't think from the error mesaage it can come from your LIBS += -lpython2.7.)

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              lfreeman6490
              wrote on last edited by
              #16

              @JonB I do not have a 'python27_d.lib' file in my python download at all, I only have 'python27.lib'. I'm looking where to get one from

              JonBJ 1 Reply Last reply
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              • L lfreeman6490

                @JonB I do not have a 'python27_d.lib' file in my python download at all, I only have 'python27.lib'. I'm looking where to get one from

                JonBJ Offline
                JonBJ Offline
                JonB
                wrote on last edited by JonB
                #17

                @lfreeman6490
                The _d suffix looks like it's looking for a debug version of the library, that's all I know.

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                • L Offline
                  L Offline
                  lfreeman6490
                  wrote on last edited by
                  #18

                  For anybody in the future that may come across this. Thanks to @JonB I was able to have in my .pro file

                  INCLUDEPATH += C:/Python27/include
                  
                  win32:LIBS += -LC:/Python27/libs -lpython27
                  

                  and then in my main.cpp file

                  #ifdef _DEBUG
                      #undef _DEBUG
                      #include <Python.h>
                  #else
                      #include <Python.h>
                  #endif
                  

                  The reason for the if loop is to circumvent the debug python.h file being loaded. By providing both routes the path to 'python.h'

                  Found from
                  https://stackoverflow.com/questions/16200997/why-doesnt-include-python-h-work

                  JonBJ 1 Reply Last reply
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                  • L lfreeman6490

                    For anybody in the future that may come across this. Thanks to @JonB I was able to have in my .pro file

                    INCLUDEPATH += C:/Python27/include
                    
                    win32:LIBS += -LC:/Python27/libs -lpython27
                    

                    and then in my main.cpp file

                    #ifdef _DEBUG
                        #undef _DEBUG
                        #include <Python.h>
                    #else
                        #include <Python.h>
                    #endif
                    

                    The reason for the if loop is to circumvent the debug python.h file being loaded. By providing both routes the path to 'python.h'

                    Found from
                    https://stackoverflow.com/questions/16200997/why-doesnt-include-python-h-work

                    JonBJ Offline
                    JonBJ Offline
                    JonB
                    wrote on last edited by
                    #19

                    @lfreeman6490 said in How to call specific Python functions from QT GUI:

                    Found from
                    https://stackoverflow.com/questions/16200997/why-doesnt-include-python-h-work

                    Good spot! That's a nasty one!

                    For anyone following this link to the stackoverflow topic, you should look at https://stackoverflow.com/a/32425901/489865 answer on that page, not just the accepted solution one.

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                    • JonBJ JonB

                      @lfreeman6490 said in How to call specific Python functions from QT GUI:

                      Found from
                      https://stackoverflow.com/questions/16200997/why-doesnt-include-python-h-work

                      Good spot! That's a nasty one!

                      For anyone following this link to the stackoverflow topic, you should look at https://stackoverflow.com/a/32425901/489865 answer on that page, not just the accepted solution one.

                      L Offline
                      L Offline
                      lfreeman6490
                      wrote on last edited by
                      #20

                      @JonB Would you know how should I proceed with my original issue, that is calling specific Python functions. The path I've been trying to down isn't getting me very far. I've been using this so far.

                      void f_pathloss::on_pb_connect_disconnect_clicked()
                      {
                          PyObject *pName, *pModule, *pDict, *pFunc;
                          PyObject *pArgs, *pValue;
                      
                          Py_Initialize();
                      
                          pName = PyString_FromString((char*)"test_program");
                          pModule = PyImport_Import(pName);
                      
                          pFunc = PyObject_GetAttrString(pModule, "test_function");
                      
                          PyXDECREF(pFunc);
                          pValue = PyObject_CallObject(pFunc, pArgs);
                      }
                      

                      where 'test_function' is in 'test_program'.py. All that test_function does is return a string that simply says "this is a c++ test". I have seen QProcess mentioned, but that seems to mainly work when you want to run the entire script, not just a single function.

                      For the code I've pasted above, once the user hits the connect_disconnect_clicked() button, I want to call a function.

                      JonBJ 1 Reply Last reply
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                      • L lfreeman6490

                        @JonB Would you know how should I proceed with my original issue, that is calling specific Python functions. The path I've been trying to down isn't getting me very far. I've been using this so far.

                        void f_pathloss::on_pb_connect_disconnect_clicked()
                        {
                            PyObject *pName, *pModule, *pDict, *pFunc;
                            PyObject *pArgs, *pValue;
                        
                            Py_Initialize();
                        
                            pName = PyString_FromString((char*)"test_program");
                            pModule = PyImport_Import(pName);
                        
                            pFunc = PyObject_GetAttrString(pModule, "test_function");
                        
                            PyXDECREF(pFunc);
                            pValue = PyObject_CallObject(pFunc, pArgs);
                        }
                        

                        where 'test_function' is in 'test_program'.py. All that test_function does is return a string that simply says "this is a c++ test". I have seen QProcess mentioned, but that seems to mainly work when you want to run the entire script, not just a single function.

                        For the code I've pasted above, once the user hits the connect_disconnect_clicked() button, I want to call a function.

                        JonBJ Offline
                        JonBJ Offline
                        JonB
                        wrote on last edited by
                        #21

                        @lfreeman6490
                        I have never done any of this. You show code, which looks reasonable, but say nothing about what happens when you call it, or step through it in debugger? @mrjj linked to an example, it looks similar. You would benefit from some error checking code here.

                        QProcess is to do with running an external program, or OS command. You can run a whole Python script that way, but I don't think it's what you should be looking at.

                        L 1 Reply Last reply
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                        • JonBJ JonB

                          @lfreeman6490
                          I have never done any of this. You show code, which looks reasonable, but say nothing about what happens when you call it, or step through it in debugger? @mrjj linked to an example, it looks similar. You would benefit from some error checking code here.

                          QProcess is to do with running an external program, or OS command. You can run a whole Python script that way, but I don't think it's what you should be looking at.

                          L Offline
                          L Offline
                          lfreeman6490
                          wrote on last edited by
                          #22

                          @JonB Well nothing happens when I do it. It builds successfully and launches the GUI, once I click the button nothing happens. There isn't an error thrown at all either. Just wanted to ask and see

                          JonBJ 1 Reply Last reply
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                          • L lfreeman6490

                            @JonB Well nothing happens when I do it. It builds successfully and launches the GUI, once I click the button nothing happens. There isn't an error thrown at all either. Just wanted to ask and see

                            JonBJ Offline
                            JonBJ Offline
                            JonB
                            wrote on last edited by
                            #23

                            @lfreeman6490
                            So start debugging that function! I take it you actually have a test_function in the test_program, else what do you expect.

                            Maybe you need the different code in https://sites.northwestern.edu/yihanzhang/2019/08/22/how-to-invoke-python-function-from-c/, I don't know?

                            1 Reply Last reply
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