Skip to content
  • Categories
  • Recent
  • Tags
  • Popular
  • Users
  • Groups
  • Search
  • Get Qt Extensions
  • Unsolved
Collapse
Brand Logo
  1. Home
  2. Qt Development
  3. General and Desktop
  4. How to call specific Python functions from QT GUI
Forum Updated to NodeBB v4.3 + New Features

How to call specific Python functions from QT GUI

Scheduled Pinned Locked Moved Unsolved General and Desktop
23 Posts 3 Posters 3.0k Views 1 Watching
  • Oldest to Newest
  • Newest to Oldest
  • Most Votes
Reply
  • Reply as topic
Log in to reply
This topic has been deleted. Only users with topic management privileges can see it.
  • 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
    1
    • 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
      0
      • 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.)

        L 1 Reply Last reply
        1
        • 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.)

          L Offline
          L Offline
          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
          0
          • 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.

            1 Reply Last reply
            1
            • 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
              3
              • 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.

                L 1 Reply Last reply
                2
                • 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
                  0
                  • 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
                    0
                    • 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
                      0
                      • 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
                        1

                        • Login

                        • Login or register to search.
                        • First post
                          Last post
                        0
                        • Categories
                        • Recent
                        • Tags
                        • Popular
                        • Users
                        • Groups
                        • Search
                        • Get Qt Extensions
                        • Unsolved