How to handle a question whose type changes but name doesn't?

[jnm]

Example form choices:

list_name	name	label
service	carry_out	Carry-out
service	sit_down	Sit-down
service	delivery	Delivery

Example form survey:

name	type	label
restaurant_name	text	What's the name of the restaurant?
restaurant_type	select_one service	What service does this restaurant offer?

An export for this form might look like:

restaurant_name	restaurant_type
Duchess	carry_out
Leméac	sit_down

Now, change the survey to:

name	type	label
restaurant_name	text	What's the name of the restaurant?
restaurant_type	select_multiple service	What services does this restaurant offer?

Add some more submissions, and an export might look like:

restaurant_name	restaurant_type	restaurant_type/carry_out	restaurant_type/sit_down	restaurant_type/delivery	version
Duchess	carry_out				1
Leméac	sit_down				1
Masala Kitchen	carry_out sit_down delivery	1	1	1	2
Jerry Carryout	carry_out	1	0	0	2

That wouldn't actually happen, because only the first definition of restaurant_type is used. However, after #149 is fixed, a change from select_one to select_multiple should be okay.

So, what's the problem?

Consider a change the other way, from a select_multiple to a select_one. Consider a select question whose choices are removed in a later version. Consider a geopoint that changes to a text.

Should fields whose type changes but name remains the same just be treated as separate fields altogether? Or should we treat them with more nuance? Presumably, changes between types that export to only one column should be okay.

https://www.flowdock.com/app/kobotoolbox/kobo/threads/B2sSngalmsnI5QXU-F75efX36Ip

[joshuaberetta]

Additionally: #60 (comment)