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#16 Today 07:33:35
Re: Callback for saving own new fields
Ah yes, that’s true about the pre/post in this case. Sorry, I didn’t take account of the actual callback name article_submit, d’oh.
The ampersand treats the passed value by reference. So, rather than making a local copy of the variable and working on that, which gets destroyed when the function exits (barring any return), it operates on the external variable directly.
Unless a callback explicitly assigns whatever you return to its own (or another) variable, returning something from a callback function will do nothing. In those cases, an ampersand usually works better.
So, you can usually return something from these callbacks:
$some_variable = callback_event($evt, $stp, $data);But you would use an ampersand on your received variable in your function signature if the callback was one of these:
callback_event($evt, $stp, $data);
callback_event_ref($evt, $stp, $data);Annoyingly there’s no way to know which is which, without looking at the code, so one of the things I’d like to do is adopt a solid naming convention to make it obvious from the callback event/step/pre which type it is.
Generally though, if it’s a callback_event_ref then you need to use an ampersand. As you found, your variable name doesn’t need to match the external one: that’s your reference copy, like a pointer to the external variable you’re manipulating.
Hope that helps.
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