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I am seeing an unexpected result with the following code:

(I actually have two issues, but the latter is prolly just me.?. I'll explain more at end)




The first issue I am seeing is with the RegisterCallback construct. The issue is that the code, as reflected above, yields an A4 error with the DLLCall. If, however, I change the RegisterCallback construct line to:

OR

If I remove the default parameter, altering the functions's definition to:

It works fine and Error_Level is not set on the DLLCall.

This kicked my arse a bit as I was thinking that an error with the RegisterCallback construct would have been able to be trapped with ErrorLevel, but that is not the case...

Is this considered to be normal operation?

...

Ok, the 2nd query: Why is the function printing the parameter text just file for a conventional call, but only prints the pointer when called via DLLCall? Is the DLLCall or RegisterCallback constructs in error?

Do I need to have the function be smarter and coded to react differently if called via a callback vs. a conventional call?

This seems to be a bit of an bug as I would expect the function's code to behave the same in both cases.?.

Thoughts? Plz advise. TIA. -t

_________________
When replying, please feel free to address me as Tod. My AHK.net site...

I am seeing this behavior on both 1.0.48.05 and 1.0.90.00_ANSI.

Just a bit more info to consider.

-t

_________________
When replying, please feel free to address me as Tod. My AHK.net site...

You passed too many parameter. ParamCount: "If entirely omitted, it defaults to the number of mandatory parameters in the definition of FunctionName."
If RegisterCallback returned a callback address, it succeeded in doing what you told it to do.
If you call the function directly, the callback has nothing to do with it. For callbacks, "All incoming parameters are integers between 0 and 4294967295."
How should the callback know what type of value you gave it?

Touche'. /me is a bit thick skulled at times. Thank you.

Yes, I figured this out here. Thank you.

Touche' (once again...). That cranium maximus on top of muh neck is embarrassing at times.

One approach I can think of is to have some code at the beginning of the function to test the parameter to see if it is a pointer and pull in the data conditionally, and then run the function as intended.

Another is to have optional parameters that are used only by the callback, and have some specific code therein (or a call to a tool function) to pull in the data.

Any other suggestions (or best practices) that would allow one to leverage a function so that it can be used both conventionally as well as via a callback?

In closing, thank you for helping to draw my attention to the obvious. Sometimes one can get too close to what they are working on such that they lose objectivity. I think I suffered that fate here.

If you celebrate: Merry Christmas. If not, have a great day!

-t

_________________
When replying, please feel free to address me as Tod. My AHK.net site...

This approach is functional...

_________________
When replying, please feel free to address me as Tod. My AHK.net site...