DateTime? compare

[zdenek hostinsky]

Hello

when comparing datetime, there is a problem with null value

sharpkit generates

for

if (equipment.EstimatedDeliveryTime == null)

sharkkit correctly generate 

 if (System.DateTime.op_Equality(equipment.EstimatedDeliveryTime, null)){

hovewer folloging throws an expception

Compare: function (t1, t2) {

return t1.valueOf() - t2.valueOf();

},

Z

[Dan-el Khen]

Can you tell me what exception it throws?

Thanks

D.

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[Zdenek Hostinsky]

Hello

 

Null reference – as t2 is null

 

Zdenek

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[Dan-el Khen]

I see, well, DateTime objects are never supposed to be null, can you reproduce this issue? I want to trace back how you got to that.

Thanks
D.

[Zdenek Hostinsky]

Simply by using DateTime?

 

Even using that

 

C# code like

 

if (equipment.EstimatedDeliveryTime == null)

is converted to comparion like

 

 if (System.DateTime.op_Equality(equipment.EstimatedDeliveryTime, null)){

 

 

 

simple workaround is to modify the C# code like

 

if (equipment.EstimatedDeliveryTime.HasValue == false)

 

 

so not a big issue – but probably worth fixing

 

(unless not fixed already, I’m on sharpkit 5.4.4)

 

Z

[Dan-el Khen]

But if EstimatedDeliveryTime is a struct, you're not supposed to be able to compare it with null.

D.

[Zdenek Hostinsky]

If it is DateTime? ( nullable type) I can really do that J

[Dan-el Khen]

So it's a Nullable<DateTime> and not a datetime, and that explains it much more. I'm not sure if DateTime equality should be called in this case so I'm kind of surprised here.

Basically you're saying that:

DateTime? x = null;

var b = x == null;

Will cause DateTime.op_Equality(x, null) ?

I'll happily check this, can you just verify that this is the case please?

Thanks
D.

[Zdenek Hostinsky]

Yes – talking about “datetime?” ( or Nullable<DateTime> - whatvever version you prefer)

 

And what you are describing is exactly the case

 

 

Thanks

[Dan-el Khen]

You're right, verified. It seems that DateTime equality methods are called instead of Nullable.Equals and compare is called (or implemented). Firstly, I need to check if this is caused by the parser or sharpkit.

Anyway, added:

https://github.com/SharpKit/SharpKit/issues/15

Thanks for detecting and reporting this!

Cheers

D.