[dart-misc] Clarification for `final` vs `var` in local scope.

[jtknox via Dart Misc]

(If there's an existing group for style related questions, in particularly
clarifications of Effective Dart, please let me know and I'll post there
instead).

I am aware of the preference to fields-and-top-level-variables-final
<https://www.dartlang.org/guides/language/effective-dart/design#prefer-making-fields-and-top-level-variables-final>,
but what about local variables. Consider something like:

set property(String value) {
var oldProperty = _property;
_property = value;
notifyChange(oldProperty, _property);
}

I *could* make `oldProperty` final, but that feels overly verbose. Is there
a consensus on using `var` vs `final` in these cases?

[Randal L. Schwartz]

jtknox> I *could* make `oldProperty` final, but that feels overly verbose. Is there
jtknox> a consensus on using `var` vs `final` in these cases?

If it were a longer routine, it might be a nice assertion that nobody
should update the value later.
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['Lasse R.H. Nielsen' via Dart Misc]

Post by jtknox via Dart Misc
(If there's an existing group for style related questions, in particularly
clarifications of Effective Dart, please let me know and I'll post there
instead).
I am aware of the preference to fields-and-top-level-variables-final
<https://www.dartlang.org/guides/language/effective-dart/design#prefer-making-fields-and-top-level-variables-final>,
set property(String value) {
var oldProperty = _property;
_property = value;
notifyChange(oldProperty, _property);
}
I *could* make `oldProperty` final, but that feels overly verbose. Is
there a consensus on using `var` vs `final` in these cases?

There is no consensus, and the style guide leaves it up to you (it has the
"be consisitent with the surrounding code" rule, though).

Some people think you should make local variables final if you can. Others
think it's unnecessary noised.

Since the only code that will ever access that variable is code in the same
function, it provides not *compiler* benefit to mark a variable as final.
The compiler is quite capable of detecting that there are no assignments to
the variable.
If the function is short, there is probably also no human reader benefit.
If the function is long, maybe you should make shorter functions :)

/L

Post by jtknox via Dart Misc
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