Allow = as separator for named parameter default value.

[floitschG]

We have foo([x = 42]) and foo({x: 42}) as the ways to specify default values for parameters.

That means that changing your function from a positional parameter to a named parameter is not just changing the [] to {}, you also have to change = to : - but it still means exactly the same thing (default value). This breaks the rule about similar things having similar syntax.

Even without changing from one type of parameter to another, I still regularly write = for named parameters. There is simply nothing to remind me that it's not =.

It might be cute that it 1) looks like a map or 2) looks like how the function is called, but the former is only true in trivial cases and the latter isn't helping anyway - it's not like positional parameter default values looks like arguments in a function call.

• language spec (Allow = as separator for named parameter default value. #27634)
• analyzer (Allow = as separator for named parameter default value #27635)
• intelliJ
• dart2js (Allow = as separator for named parameter default value #27636)
• vm (Allow = as separator for named parameter default value #27637)

[kasperpeulen]

This is also how named default parameters are done in ES2015:

[lrhn]

(Closing this, assuming the "intellij" checkmark is correct, the remaining ones were fixed by the same CL).

[munificent]

Magnificent! If only all language features could be implemented in one giant commit!

You should also update the CHANGELOG and otherwise let people know that this change exists. 🎉

[lrhn]

Changelog was ac76d3e
About letting people know ... probably a good idea :)

[lyrachord]

OK, you do, I do not. It's the life. 👎

= should just be the assignment symbol.
There is no semantics between the default value with name and the name.
JS version is not brilliant reason for this change.