Champion "Mix Declarations and Variables in Deconstruction"

[gafter]

• Proposal added
• Discussed in LDM
• Decision in LDM
• Finalized (done, rejected, inactive)
• Spec'ed

See

• Allow mixed deconstructions, with both assignments and declarations roslyn#15050

[nelsonlaquet]

This feature would clean up code that propagates statuses and errors via tuples, similar to error handling in Go.

For example:

Err err;
Ret1 ret1;
(ret1, err) = await Func1();
if (err) return (default, err);

Ret2 ret2;
(ret2, err) = await Func1();
if (err) return (default, err);

Could turn into:

Err err;
(var ret1, err) = await Func1();
if (err) return (default, err);

(var ret2, err) = await Func1();
if (err) return (default, err);

Which is much easier to read IMO.

[mms-]

Unless there are good technical reasons not to, this definitely should be implemented, it is just natural.

[alrz]

Linking #3304 here since I believe they belong to the same bucket - would be a nice-to-have syntax relaxation for the deconstruction feature.

(var sum, count: someExistingLocation) = e;

[jcouv]

This was merged under LangVersion=Preview as part of VS 16.10. Thanks @YairHalberstadt for the contribution!