Subject Re: VARIABLE DECLARATION From Mustansir Ghor <mustan31@hotmail.com> Date Sun, 11 Mar 2018 08:36:10 -0400 Newsgroups dbase.getting-started Dear Andy This is real. Great. Thank you. I has cleared many issues. I had used similar lines in rendering a report that is before render when you put program in memory (set procedure to xyz.rep) and open report class (r = new xyzreport()). After this I could put some of report text like form text by r.pagetemplate1.title.text =form.text So all in all it means f = new xyzform() creates object in memory and windows assigns a handle to it. If xyzform class is not therei n  current file then we have to define it by Set procedure to xyz.wfm  which loads the program in memory Thank you Best Regards Mustansir Andy Taylor Wrote: > Akshat, Mustansir > > Let me take you both through form instantiation and variable scope as we run through the code below: > > mipdname = ""               // the variable mipdname now exists as a private variable within memory > > ** END HEADER -- do not remove this line > // Generated on 07/03/2018 > // > parameter bModal > local f                            // a local memory variable is created   > f = new ghor22Form()    // the form now exists in memory as an encapsulated object referred to via f   > > if (bModal)                     // assume bModal is false for the moment >     f.mdi = false // ensure not MDI >     f.readModal() > else >     f.open()                     // the form opens - this assigns a windows handle to the object and it appears on screen > endif > > At this point the rest of the code in the form is irrelevant, it belongs to the class definition of ghor22Form, it doesn't >  get run... it was run above as part of "f = new ghor22Form()".  So we have effectively reached the end of the wfm >  code. In your mind think "return". > > Therefore, once the form opens, f, which is local in scope, disappears. > What about mipdname? Well, that was private in scope and as we have hit a return point on the processing of ghor22.wfm > it too will disappear. > > The only thing left (hanging in memory) is the form. The form can, obviously, no longer see f, mipdname or bModal. > The reason the form stays in memory is because windows has an open handle to it.  Once you close it the form will > also disappear from memory.  This is handled automatically by dBase and works as expected UNLESS your programming > has managed to insert another memory pointer to that form, in which case it will still exist in memory. That, however, is > beyond the scope of this discussion. > > As Mervyn has said if you insist on using a memory variable which is visible to the form you could start with > Public mipdname; mipdname = "" > This would be visible to every object in dBASE, not only the form. It would NOT be private in scope to this form and > could get messy when opening multiple forms... you'd have to have a different  variable name for each form. You also > have to be sure to release the public variables when the forms close. >   > The better way to do what you want is to make the midpname variable a property of the form.  That way it will disappear > when the form gets released from memory but remain in scope to the form and only that form.  The way to do this easily > is within the form class definition: > function onOpen; form.mipdname = ""; return > > Note that you cannot write this as: > function onOpen; mipdname = ""; return > Why? Because you got to a return point... OnOpen has finished processing and the private variable mipdname disappears from memory.... > > So the message is stop trying to use memory variables in forms, they don't work the way you think they should unless they >  are part of a method or, for a private variable, a chain of methods. > Instead of memory variable start thinking "a property of the form is what I need". > > Now, turning to Akshat's methods. Akshat duplicates a copy of the bootstrap above the header line and rewrites it knowing > that the designer won't mess with it. This is a neat trick.  Could you write your memory variable in there? Yes. If you move it > to make it a form property. See below: > > parameter bModal > local f > f = new ghor22Form() > f.mipdname = ""          // sneaky additional code adds a property before the form is opened. > if (bModal) >    f.mdi = false // ensure not MDI >    f.readModal() > else >    f.open() > endif > > ** END HEADER -- do not remove this line > --designer code follows... > > Akshat also notes that his method will work with readmodal() but not open().  This is because with readmodal everything stops, > no further processing occurs and we don't get to the return point after processing the wfm code until AFTER the readmodal > form also closes.  That is why a readmodal form would also be able to see mipdname and bModal but not, of course, f.... > > One final point to note is that it does take some time after opening a form for any variables such as mipdname to be released > from memory. This is why it may be possible to access mipdname using the onOpen event of a form or any code that is triggered > very quickly. Wait any length of time however and mipdname will not remain accessible in memory.  This is probably why > Mustansir's first method of using mipdname worked and the other two didn't. > > I hope this rather long-winded explanation helps (this sort of thing took me long enough to figure out some years ago). > Andy.