Change Variable block accepts drag/drop of a block

[hansdejongehv]

See this screenshot:

The top change block was created by using the drop down option and selecting the variable from the list.
In the bottom change block, the variable "test variable" was dragged and dropped in. Which the block accepts as only one. Neither Set, Show Variable nor Hide Variable accepts this.

It was very confusing for students and it took me a while when called in to discover what the cause was. Can this be fixed please? Either allowing it and then doing it correctly or blocking the drag/drop on this block like on Set, Show Variable and Hide Variable.

Can this be fixed please?

[brianharvey]

Good catch, this is a bug in Snap! too.

In the early days of BYOB, we allowed dropping a variable onto that menu, with the same semantics as dropping the variable on any other input: The value of the variable became the value of that input. For SET and friends, that was very occasionally useful, when a variable's value was the name of another variable. It was a very common technique, called "indirect addressing," in the days when people programmed in assembler, but rather obscure these days.

Anyway, we learned that it really confused users, who expected that dropping a variable onto that slot would be the same as selecting that variable in the menu, so it would set the variable itself rather than setting the variable whose name was the value of the given variable. So we decided just to disallow the drop altogether. But apparently CHANGE doesn't disallow it in Snap!. We should fix that.