Cannot destructure a Readonly Tuple #17563

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1. jcalz commented on Aug 2, 2017

   

   Joe Calzaretta (jcalz)

   on Aug 2, 2017

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   This is probably a limitation of the Readonly<> that causes it to lose the "array-ness" of the tuple type. You can work around it as follows:

   type ReadonlyTuple = Readonly<[string, number]> & [string, number];
   const rt: ReadonlyTuple = ['string', 2]
   rt[0] = 'zero'; // error as expected, still read-only
   const [rs,rn] = rt // no error, accepts as array type

   👍React with 👍2Reacted by Steve Lee and Sean Flanigan
2. olegdunkan commented on Aug 2, 2017

   

   olegdunkan

   on Aug 2, 2017

   Last edited by olegdunkan

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   ReadonlyTuple is mapped type, destructing requires array like type in your case

   👍React with 👍1Reacted by Steve Lee
3. Mohamed Hegazy (mhegazy)

   added

   Design LimitationConstraints of the existing architecture prevent this from being fixedConstraints of the existing architecture prevent this from being fixed

   on Aug 23, 2017
4. mhegazy commented on Sep 7, 2017

   

   Mohamed Hegazy (mhegazy)

   on Sep 7, 2017

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   Automatically closing this issue for housekeeping purposes. The issue labels indicate that it is unactionable at the moment or has already been addressed.
5. Mohamed Hegazy (mhegazy)

   closed this as completedon Sep 7, 2017
6. microsoft

   locked and limited conversation to collaborators on Jun 14, 2018