There are different ways of approaching this.
If your code needs to be totally generic, bundle it into a procedure file (alternatively, if you need functions to relate to other function's values and have a lot of this, you can bundle it all into a custom class and assign properties for the shared values).
If, however, the code only needs to be accessed on a form or a collection of forms, put methods on the form (and, if a collection of forms, save the form as class). You should always avoid putting code in the click method of a button - what if you need to call it from somewhere else on the form? Click methods should just call form methods or functions/procedures/class methods.

It's all down to "how many places need this code and where?"

>I have various forms that run reports, and a lot of time, do a fair bit of processing before displaying the report.
>
>Whenever I have created these forms, I just put the processing code in the Click() of the OK button.
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>I'm sure this isn't good practice in OOP, can anyone give me their views as to where it would be appropriate to place my "report processing" code. I would imagine it was better to have huge chunks of code in a central spot, then have the form fire it off from there.
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>Can anyone advise?
>Thanks
>Kev