CreateObject Misconception

[csr]

I must have a misconception about CreateObject.

This code fails at the last line and I do not understand why ?

The error is ... OutputReport.scx does not exist !

I thought I had created a form object and was not calling that form. I guess not.

OutputReport = CREATEOBJECT("my_frm&quot
outputReport.caption = "Report Output"
OutputReport.AddObject("cmdVIEW", "my_cmd&quot
OutputReport.AddObject("cmdPRINT", "my_cmd&quot
DO FORM OutputReport

Don

 

[csr]

Correction to that last line of my message ...

I thought I had created a form object and WAS calling that form. I guess not.



Don

 

[MadTown]

Don,

OutputReport = CREATEOBJECT("my_frm&quot
outputReport.caption = "Report Output"
OutputReport.AddObject("cmdVIEW", "my_cmd&quot
OutputReport.AddObject("cmdPRINT", "my_cmd&quot
OutputReport.Show()

The CREATEOBJECT creates the form it is just hidden until you call the show method.

 

[Mike Lewis]

Don,

Your code is in fact trying to create the form twice.

You can use CREATEOBJECT() to create a form (or, more correctly, an instance of a form) based on a form class. It will return a reference to the form, which you can then store in a variable (OutputReport in your case).

Alternatively, you can use DO FORM to create an instance of the form. To do that, you need a form file, that is, an SCX file. In your case, there is no SCX called OutputReport, so the DO FORM will fail.

The solution is to use either CREATEOBJECT() or DO FORM, but not both. Also, given that the object created by CREATEOBJECT() is always initially invisible, you need to either set its Visible property .T. or call its Show method to make it visible.

Mike


Mike Lewis
Edinburgh, Scotland

http://www.ml-consult.demon.co.uk

 

[csr]

Thanks for your help with this. It makes more sense now.

However, this exercise has led me to a solution that seems easier ...

I created a class (with all the buttons I need) and am not using simply ...

outputReport = createObject("my_frm_output_report_options&quot
outputReport.show()

The problem I now have is that I would like to send a result from this form to a parameter ... like in
do form xyz to nSomeParamter.

Is that possible with the CreateObject / Show method ?





Don

 

[wgcs]

You can just create a property in the form class like "FormResult", and do something like:

outputReport = createObject("my_frm_output_report_options")
outputReport.show()
if outputReport.FormResult>1
  * whatever
endif

 

[Mike Lewis]

Don,

I think you mean that you want to return a result from the form. The usual way to do that is to use a RETURN command in the form's Unload. Then, call the form like this:

do form xyz to nSomeParamter

and nSomeParameter will acquire whatever value you return.

However, for this to work, the form has to be modal.

Mike


Mike Lewis
Edinburgh, Scotland

http://www.ml-consult.demon.co.uk

 

[csr]

Mike ...

You are correct about what I wish to do. However, I wish to use the createObject() method ... not the DO FORM method.

wgcs ...

Your solution seems to make sense.
However, it brings up a question in my mind.

My form is modal. When I execute the SHOW() method my form "shows itself" and waits for me to make my selection.
Then (inside the form) I execute thisform.release()

I am wondering if the form is still available to find out what the value of outputReport.FormResult is after the form has been released.

And if it is ... how do I get the form out of memory entirely. I mention this because I am getting some messages about something still being in memory when I attempt to modify the base class for this form.





Don

 

[wgcs]

You found the one gotcha... However, instead of using
THISFORM.Release() to get rid of the form, just use:
THISFORM.Hide()
(which, logically, is the opposite of using THISFORM.Show() to start showing the form)

To get rid of the form entirely, either just let the variable go out of scope that references the form, (outputReport), or explicitly release it when you're done with it:
RELEASE outputReport

 

[white605]

from Mikelewis above:
You can use CREATEOBJECT() to create a form (or, more correctly, an instance of a form) based on a form class. It will return a reference to the form, which you can then store in a variable (OutputReport in your case).

Alternatively, you can use DO FORM to create an instance of the form. To do that, you need a form file, that is, an SCX file. In your case, there is no SCX called OutputReport, so the DO FORM will fail.

Light bulbs come on for me after reading this post, but they also raise more questions - Is there a way to take existing forms and convert them eaisly to code, and not store and distribute them?

 

[wgcs]

One thing you can do is create the form visually in the Class Designer, based on the "Form" baseclass (or based on your own subclass of "Form&quot and save it in a VCX file,

Or you can write your form as code using the:
DEFINE CLASS myform AS Form
ENDDEFINE
syntax.

Or you can create your form using MODI FORM, then, while editing it, choose [ File -> Save As Class ] to save it into a VCX,

Or you can create your form however you like, get it into a VCX however you like, then load the VCX in the "Class Browser" and click the toolbar button "View Class Code" which will attempt to convert the VCX class into a DEFINE CLASS...ENDDEFINE definition. (I say "attempt" because it isn't always successful: it doesn't handle nested objects very well)

 

[Mike Lewis]

White605,

If you want to create a PRG file containing a DEFINE CLASS for an existing form, the easiest way is to open the form in the class browser, select "View Class Code" and save the resulting code in a PRG.

Mike


Mike Lewis
Edinburgh, Scotland

http://www.ml-consult.demon.co.uk

 

[Mike Lewis]

Don,

I'd go with Wgcs's suggestion. When you hide a form, it becomes, in effect, modeless. You can then access its properties and call its methods from the calling code.

So, create a form property to hold the value that you want to return (let's say you call it nRetVal). You can then do this:

DO FORM xyz
xyz.Show
* Do something with xyz.nretVal
xyz.Release

Give it a try.

Mike


Mike Lewis
Edinburgh, Scotland

http://www.ml-consult.demon.co.uk

 

[csr]

This turned out to be highly informative. Thanks to all for your contribution.

the gist of what I finally ended up doing was this ...

Not a bad solution considering that the use of the private variable cMode is completely hidden within code in a library routine so I will not have to remember how it works.


function outputReport(cReportForm)
private cMode, outputReport
cMode = []
outputReport = createObject("my_form_outputreport&quot
outputReport.show() && this form modifies cMode
do case
case cMode = "PRINT"
report form (cReportForm) to print prompt noconsole
case cMode = "VIEW"
report form (cReportForm) preview noconsole
otherwise
endcase
return .t.


I may eventually (could be sooner rather than later) go back and do this over using the createObject / AddObject technique so I do not have to have the "my_form_outputreport" form prebuilt in a VCX file. But for now, this works fine. Thanks again.



Don

 

[Mike Lewis]

Don,

Looks like you've got a nice neat solution. The only suggestion I would make is that you make cMode a property of the form rather than a private variable. That way, the form won't be dependent on being called from that particular piece of code, and that would be a more OOP-like approach. On the other hand, the code you have written should also work fine, so go with it.

Mike


Mike Lewis
Edinburgh, Scotland

http://www.ml-consult.demon.co.uk

 

[csr]

Mike ...

If I make (cMode) a property of the form then I am back
to ....

(Close form with HIDE rather than RELEASE)
cResult = outputReport.cMode
outputReport.release()

Correct ?





Don

 

[Mike Lewis]

Don,

Yep, that looks right. As I said, it's a slightly more OOP-like way of doing it.

Mike




Mike Lewis
Edinburgh, Scotland

http://www.ml-consult.demon.co.uk

 

[csr]

Well, it is now more oop-like. I rebuilt it to incorporate those latest suggestions. It works just fine.
Thanks.


Don

 

[Mike Lewis]

That's great, Don. Glad it's working.

Mike


Mike Lewis
Edinburgh, Scotland

http://www.ml-consult.demon.co.uk