MADateDescription and nil objects

[Dominique Dutoit]

Hi Lukas

>> 3. Delete the content of the field, MADateDescription complains about
>> an invalid date format.
>
> Sorry, I am unable to reproduce.

Hum, I shouldn't trust my own memory. In fact, the problem has  
nothing to do with the date format but when Magritte is committing  
the changes to the original object.

I can reproduce the problem with a form structure (Pier.72, Magritte. 
142).

1) Create a form
2) Edit the meta of that form
3) Add a date element
4) Save the element
5) Save the meta

6) Edit the form
7) Assign a date
8) Save the form

9) Edit the form
10) Select the date and delete it (the field should be empty)
11) Save the form

At that moment, I get this traceback:

MessageNotUnderstood: UndefinedObject>>start
UndefinedObject(Object)>>doesNotUnderstand: #start
	self		nil
	temps
	aMessage	start
Date(Timespan)>>=
	self		2 March 2006
	temps
	comparand	nil
	inst vars
	start		2006-03-02T00:00:00+00:00
	duration 	1:00:00:00
[] in Dictionary>>= {[:assoc | (aDictionary at: assoc key ifAbsent:  
[^ false]) = assoc v...]}
	self		a Dictionary(a MADateDescription label: 'Date' comment: nil- 
 >nil a MAStringDescription label: 'Title...etc...
	temps
	aDictionary	a Dictionary(a MADateDescription label: 'Date' comment:  
nil->2 March 2006 a MAStringDescription labe...etc...
	assoc		a MADateDescription label: 'Date' comment: nil->nil
	inst vars
	tally 		2
	array		#(nil nil a MAStringDescription label: 'Title' comment: nil- 
 >'Untitled' nil a MADateDescription labe...etc...
Dictionary(Set)>>do:
	self		a Dictionary(a MADateDescription label: 'Date' comment: nil- 
 >nil a MAStringDescription label: 'Title...etc...
	temps
	aBlock		[] in Dictionary>>= {[:assoc | (aDictionary at: assoc key  
ifAbsent: [^ false]) = assoc v......etc...
	index		5
	each		a MADateDescription label: 'Date' comment: nil->nil
	indexLimiT	6
	inst vars
	tally		2
	array		#(nil nil a MAStringDescription label: 'Title' comment: nil- 
 >'Untitled' nil a MADateDescription labe...etc...
Dictionary>>associationsDo:
	self		a Dictionary(a MADateDescription label: 'Date' comment: nil- 
 >nil a MAStringDescription label: 'Title...etc...
	temps
	aBlock		[] in Dictionary>>= {[:assoc | (aDictionary at: assoc key  
ifAbsent: [^ false]) = assoc v......etc...
	inst vars
	tally		2
	array		#(nil nil a MAStringDescription label: 'Title' comment: nil- 
 >'Untitled' nil a MADateDescription labe...etc..