LiveCode Forums.

Can anyone tell me why you would use a custom handler as on this page http://lessons.livecode.com/m/4071/l/16 ... ers-part-1 with this syntax in preference to a custom command with this syntax as on this page http://lessons.livecode.com/m/4603/l/44 ... g-a-button?

Or are these two different names and syntaxes for the same thing?

The user guide entry for Custom Commands gives the syntax but doesn’t mention the syntax .

The app building course on many occasions uses but I don’t recall seeing the syntax .


Thanks!
Jim

Hi.

I go way back. I use "on", not "command". But these are synonyms.

Craig Newman

Thanks Craig - good to know! I thought I was maybe missing something since it wasn't clear in the user guide or dictionary.

Best wishes,
Jim

The "command" token is meant to help distinguish between messages the engine sends and custom handlers you write yourself. So you would use "on mouseUp" because that's a built in message, and "command myOwnHandler" for those you've written.

They do act as synonyms functionally.

jacque wrote:The "command" token is meant to help distinguish between messages the engine sends and custom handlers you write yourself. So you would use "on mouseUp" because that's a built in message, and "command myOwnHandler" for those you've written.

Exactly!

And once upon a time the mothership advised us to really make this difference
due to possible future changes in the engine, which would make this actually neccessary!

Which however did not happen so far...

Jacque, Klaus,

Thanks for your help. I hope at some point the user guide, lessons and dictionary will be updated to say these are synonyms and include the explanations you've given.

Best wishes,
Jim

I am constantly being reminded that synonyms are discouraged. Nonetheless, these are synonyms and I use them in the manner described above, with the addition that anything that will be the object of a "send" or "dispatch" command I treat as a message, and therefore use the "on" format.

The "on" format has been part of the language since the days of the dinosaurs, and changing that would break nearly every stack in existence. The "command" format, while newer, is now a part of the language, and thus also won't change without breaking backward compatibility.

Why are synonyms discouraged? Having multiple ways to write the same thing allows more folks express themselves in a manner that suits them. It also makes the language feel more natural and less syntactic. If you have ever yelled at your phone because Siri/Cortana/Alexa/Google Now are soooooooooooooooooooo STUPID, you get the idea.

My guess is the team follows Churchill rather than Orwell.
But at any rate, I think the reasoning is that too many choices confuse users.
Go figger,