7.3.4 Command Line Program Front End

This example is a simple front end to the unix "cp" command that demonstrates the use of the MrmNcreateCallback to enter the widgets created by UIL into module __main__'s dictionary. This is somewhat cleaner than having to find the UIL-created widgets using NameToWidget. The files involved are panel_cp.uil, panel_cp.uid and panel_cp.py.

    module cp_front_end
    version = 'V1.0'
    names = case_sensitive

    procedure PyEval(string);

    object main : XmBulletinBoard {
        arguments {
            XmNwidth = 300;
            XmNheight = 400;
        };
        controls {
            XmText src_file;
            XmText dst_file;
            XmPushButton button;
        };
    };

    object  src_file : XmText {
        arguments {
            XmNy = 0;
            XmNx = 10;
            XmNwidth = 280;
            XmNheight = 40;
            XmNeditMode = XmSINGLE_LINE_EDIT;
        };
        callbacks {
            MrmNcreateCallback = procedure PyEval("OnCreate('src_file_w')");
            XmNvalueChangedCallback = procedure PyEval("OnValueChanged()");
        };
    };

    object  dst_file : XmText {
        arguments {
            XmNy = 60;
            XmNx = 10;
            XmNwidth = 280;
            XmNheight = 40;
            XmNeditMode = XmSINGLE_LINE_EDIT;
        };
        callbacks {
            MrmNcreateCallback = procedure PyEval("OnCreate('dst_file_w')");
            XmNvalueChangedCallback = procedure PyEval("OnValueChanged()");
        };
    };

    object  button : XmPushButton {
        arguments {
            XmNy = 110;
            XmNx = 10;
            XmNwidth = 100;
            XmNheight = 40;
            XmNlabelString = 'Do Copy';
            XmNsensitive = false;
        };
        callbacks {
            MrmNcreateCallback = procedure PyEval("OnCreate('button_w')");
            XmNactivateCallback = procedure PyEval("DoCopy()");
        };
    };

    end module;

    uil panel_cp.uil -o panel_cp.uid

    #!/usr/local/bin/python

    import posix, os, sys, Mrm, Xm, Xt

    # -----------------------------------------
    def OnCreate(name):
        # insert name=__widget__ into __main__'s dictionary
        sys.modules['__main__'].__dict__[name] = __widget__

    # -----------------------------------------
    def OnValueChanged():
        if len(src_file_w.TextGetString()) > 0 and \
           len(dst_file_w.TextGetString()) > 0:
            button_w.sensitive = 1
        else:
            button_w.sensitive = 0

    # -----------------------------------------
    def DoCopy():
        cmd = 'cp '
        cmd = cmd + src_file_w.TextGetString() 
        cmd = cmd + ' '
        cmd = cmd + dst_file_w.TextGetString()

        print cmd
        posix.system(cmd)
        sys.exit()

    # -----------------------------------------
    def main():
        top_level = Xt.Initialize()

        mrm_hier = Mrm.OpenHierarchy("panel_cp.uid")
        main_w = mrm_hier.FetchWidget("main", top_level)

        main_w.ManageChild()
        top_level.RealizeWidget()

        Xt.MainLoop()

    main()

This example demonstrates using the OnCreate MrmNcreateCallback to access the __widget__ symbol and insert an entry in the __main__ module's dictionary for the XmText and XmPushButton widgets declared in the UIL. This makes these widgets accessible as Python-wrapped widget objects to the OnValueChanged and OnCopy callback routines, without having to pass the widgets to these callbacks in the UIL tag argument.

Another way to accomplish this is to insert the names into the __main__ namespace explicitly in main(), for example:

    global src_file_w, dst_file_w
    
    ...
    main_w = mrm_hier.FetchWidget("main", top_level)
    src_file_w = main_w.NameToWidget('src_file')
    dst_file_w = main_w.NameToWidget('dst_file')

Here, 'src_file' and 'dst_file' are the widget's names as specified in the UIL, and NameToWidget is used to find the widgets, obtain Python wrapped widget objects, and initialize src_file_w and dst_file_w global variables.