Compiler behavior on Select Case

[Lunasole]

Hi. Recently I've misspelled on "Case" statement (typed ":" instead of ","), and that caused some silent bug in my program, because case options after first one were never triggered.

It's generally not a bug, rather some kind of (syntax) problem occuring in such case.
There are 3 examples showing that:

1

Code: Select all

; Example 1, compiler doesn't see any problem and #CONST_1 is matching in Select
EnableExplicit

#CONST_1 = 3
#CONST_2 = 4
Define A = #CONST_1

Select A
	Case #CONST_1: #CONST_2:
		Debug A
	Default
		Debug "NO MATCH"
EndSelect

2

Code: Select all

; Example 2, compiler doesn't see any problem, but #CONST_2 is never matching in Select
EnableExplicit

#CONST_1 = 3
#CONST_2 = 4
Define A = #CONST_2

Select A
	Case #CONST_1: #CONST_2:
		Debug A
	Default
		Debug "NO MATCH"
EndSelect

3

Code: Select all

; Finally example 3, here compiler tells "duplicate label" on second Select statement, which points to a source of problem
EnableExplicit

#CONST_1 = 3
#CONST_2 = 4
Define A = #CONST_2

;1
Select A
	Case #CONST_1: #CONST_2:
		Debug A
	Default
		Debug "NO MATCH"
EndSelect

;2
Select A
	Case #CONST_1: #CONST_2:
		Debug A
	Default
		Debug "NO MATCH"
EndSelect

Checked with 5.60

[TI-994A]

The error seems to be caused by a confusion between constants and labels. For some reason using the hex symbol (#) in a label raises no errors.

Code: Select all

Case #CONST_1: #CONST_2:

In the above expression, the first colon is interpreted as a line concatenator, while the second is seen as a label.

[netmaestro]

I believe the allowing of constants to serve as labels is intended and actually quite useful for creating self-documenting code. I wouldn't like to see it change because someone made a typo in a case structure and caused a bug in their code, no offense intended.