Re: [mdt-ocl.dev] Arrow accessor conversion for non-collections

[Ed Willink <ed@xxxxxxxxxxxxx>]

Hi Alex

The purpose of the conversion is to make 0..1 properties easy to use.

Thus in 7.5.3 "Navigation over Associations with Multiplicity Zero or One" we get

    self.wife->notEmpty() implies self.wife.gender = Gender::female

so creation of Set{null} would completely invalidate the usage.

My raised issue has now been allocated Issue 14981.

Bag{} and Set{x} are not quite contradictory, just a little inconsistent. The issue suggests
changing to Bag{} and Bag{x}, so that the compile-time type is predictable. I changed
the MDT-OCL 1.3.0 synthesis of Set{x}-> to x.oclAsCollection()-> so that the null-ness
of x determines the collection content. Unfortunatel;y Collection<T> is insufficient to allow
some exiusting unit tests to work that expect Set.

    Ed


On 20/01/2010 18:35, Alexander Igdalov wrote:

Hi all,

 

The resolution of issue 10438 made `null->foo()` a synonym of `Bag{}->foo()`. As Ed has mentioned earlier this contradicts 7.5.3 which suggests wrapping the _expression_ source to a Set, i.e. `x->foo()` becomes `Set{x}->foo()` if `x` is not a collection.

 

Does anyone see why there is that exception from the general rule for null? If not I will raise an OMG issue for that.

 

Since `null->foo()` is allowed, what should it be converted to? Should it be `Set{}->foo()` or `Set{null}->foo()`? I would prefer the latter because only in this case we could construct a complete AST at compile time (see guideline at 9.6).

 

Regards,

- Alex.

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