I’m curious about what appears to me to be a confusing aspect of the 
implementation of behaviors. In short, behaviors have characteristics of an 
isolated, local extension of the message path AND characteristics of a 
concatenation of the parent control’s script. I’m raising the issue for two 
reasons: 1) to clarify how to explain behaviors to someone new to Livecode or 
just learning about the feature and 2) to question if all the features of 
behaviors are intentional or if some might be accidents of implementation and 
therefore may be eliminated in the future.

I’ve used behaviors since they were first introduced and it’s worked well for 
me to think of them as an extension of the message path from the parent 
control. However, I recently discovered that a command in a behavior script can 
directly call a handler in the parent script. Furthermore, if the same handler 
name is present in the behavior script and the parent script, the parent script 
handler is the one that runs. This capability is consistent with 
conceptualizing the behavior script as a concatenation with the parent script 
and contradicts the idea that behaviors are an extension of the message path. 

However, script level variables in a behavior are accessible only in the object 
script in which they are declared, consistent with the idea of an extended 
message path. Finally, If a handler with the same name exists in the parent 
script and a behavior script, it’s possible to execute the handler in the 
behavior either after the parent version runs or instead of the parent version 
by treating the behavior script as an independent step in the message path and 
using control structures like “pass”, “send” and “dispatch”. There may be more 
of the these types of inconsistencies but that seems more than enough to 
provoke some discussion on this list. I realize that any problems with these 
features of behaviors can easily be avoided by common sense design but some 
discussion seems warranted for the reasons I cited above. Anybody want to weigh 
in on this?

Tim Bleiler, Ph.D.
Instructional Designer, HSIT
University at Buffalo

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