Consider adding NullableRef and NullableValue wrappers #610

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1. kurtschelfthout commented on Jun 3, 2022

   

   kurtschelfthout

   on Jun 3, 2022

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   Yeah, I felt like the default has changed to "nulls are opt-in" in recent years, in F# since the beginning and in C# more recently.

   You can write a string generator that also generates nulls in whatever frequency you'd like.
2. jibbers42 commented on Jun 3, 2022

   

   jibbers42

   on Jun 3, 2022

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   Thank you, I was able to figure out the following which fails the test with nulls...

   [Property]
   public Property Test() {
     // Gen<string?> NullableString() => Gen.Frequency((1, Gen.Constant<string?>(null)), (7, ArbMap.Default.GeneratorFor<string?>()));
     Gen<string?> NullableString() => Gen.OrNull(ArbMap.Default.GeneratorFor<string?>());
   
     return Prop.ForAll(NullableString().ToArbitrary(), s => {
       return (s != null).Collect(s);
     });
   }

   I see something in the source called Nullable that looks like it gens a null 1/8th of the time and may be simpler to use, but I can't figure out how to use it. Do you have an example somewhere?
3. kurtschelfthout commented on Jun 3, 2022

   

   kurtschelfthout

   on Jun 3, 2022

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   that's in reference to https://docs.microsoft.com/en-us/dotnet/api/system.nullable-1.value?view=net-6.0 i.e. for nullable value types. So it won't help with strings.

   Should probably have NullableRef and NullableValue at this point...

   The idea to use this would be:

   public Property Test(NullableRef<string> wrapper) {
       var theStringOrNull = wrapper.Value;
       
   }
   
4. jibbers42 commented on Jun 3, 2022

   

   jibbers42

   on Jun 3, 2022

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   OK, thanks for all the help!

   Not sure if you want this issue open for "NullableRef and NullableValue", so feel free to close if not.

   👍React with 👍1Reacted by Kurt Schelfthout
5. kurtschelfthout

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   on Jun 11, 2022
6. kurtschelfthout

   changed the title [-]No null strings in 3.0.0-beta2 (C#)[/-] [+]Consider adding NullableRef and NullableValue wrappers[/+] on Jun 11, 2022
7. kurtschelfthout

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   enhancement

   on Jun 11, 2022
8. kurtschelfthout

   removed

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   on Feb 25, 2024
9. kurtschelfthout

   closed this as completedin 949537bon Oct 18, 2026