Sometimes, even if you know the framework as well as I do, you re- discover a feature that you had forgotten about. This happened tonight as I was going over the interaction between a grid and its form, so I thought I'd pass it along.

When any of the events that cause the current record pointer to move are handled by the form, it generates a dEvents.RowNumChanged event, to which grids can bind so that they can update their display. The form code looked like:

dabo.ui.callAfter(self.raiseEvent, dEvents.RowNumChanged)

and the event handler in the grid would run this code:

try: self.CurrentRow = self.getBizobj().RowNumber except AttributeError: pass

In other words, the grid knew that the row had changed, but had no idea what the new row was. It had to then get a reference to the bizobj for that grid, if any, and then ask that bizobj for its current row number.

Why is this inefficient? Because the code that raised the event *knew* the old and new row numbers; the fact that they were different was why it was raising the event in the first place. Then I remembered that you can pass data along to raiseEvent(); any keyword parameters you add are set as event data. So I changed the form code to read:

dabo.ui.callAfter(self.raiseEvent, dEvents.RowNumChanged, newRowNumber=biz.RowNumber, oldRowNumber=oldRowNum)

...and now the grid's event handler can just reference those values directly! They will have the same names as the parameter keys:

try: self.CurrentRow = evt.newRowNumber except AttributeError: pass

This may be a small savings overall, but I thought that it illustrated a handy mechanism built into the Dabo event class that you might use to improve your applications.

posted at: 18:10 | path: /Tips | permalink

The Dabo Editor now supports named bookmarks! This makes it much easier to navigate around a long document. If you want to bookmark a location, make sure that the cursor is on the desired line, and click on the button at the top with the 'M'. Select 'Set Bookmark' from the menu, and enter a brief name to help you remember what that means. You'll see a small cyan circle in the left margin by that line, indicating that it has been bookmarked.

Now navigate to somewhere else in the document. Do whatever editing you need, and then click on the 'M' button again. Note that the name you gave your bookmark is now in the popup menu. Select that, and the editor moves to that line. What's even cooler is that even if you add or delete lines, the bookmark follows the code that you bookmarked, not the line number!

posted at: 10:26 | path: /Tips | permalink