Inline if assignment instead of ternary operator with null else branch

[petrnymsa]

Use case

Many times in Flutter I've found myself writing conditional rendering using ternary operator where "else" branch returns null.

For example, a custom Widget has a parameter that will set some property of the nested widget or even add another widget to the tree.

Within Column or Row (or whenever we use array []) it is possible to use if statement, however elsewhere I am forced to use ternary operator where else does nothing other than returning null.

1. Example - simple conditional parameter:

BoxDecoration(
    gradient: gradientColors != null
        ? LinearGradient(
            colors: gradientColors!,
          )
        : null,
)

2. Example - Suppose I have some default Scaffold widget with shared settings and I can pass drawerBuilder to add a drawer to that Scaffold

return Scaffold(
      resizeToAvoidBottomInset: true,    
      ... // more shared settings etc...
      body: Padding(
        padding: padding,
        child:  ...., // shortened
      ),
      drawer: drawerBuilder != null
          ? Builder(builder: (context) => drawerBuilder!(context))
          : null,
    );

Proposal

Probably this request will need support from dart-lang itself. I am coming from React background and in JS / TS is possible to use && operator for such inline rendering without an explicit else branch. E.g, example 2 could be rewritten into

return Scaffold(
      drawer: drawerBuilder != null &&  Builder(builder: (context) => drawerBuilder!(context))l,
    );

It is maybe just personal preference, but I found this more clear than cluttering : null with a ternary operator.

[eernstg]

@petrnymsa, note that this issue might be a duplicate of other proposals, or at least similar.

In particular, #361 proposes a !! b meaning a == null ? null : b, so you could do this:

...
BoxDecoration(
    gradient: gradientColors !!
        LinearGradient(
          colors: gradientColors!, // `!` only needed if `gradientColors` is not a local variable.
        ),
)

This comment mentions some other proposals in the same area.

[petrnymsa]

@petrnymsa, note that this issue might be a duplicate of other proposals, or at least similar.

In particular, #361 proposes a !! b meaning a == null ? null : b, so you could do this:

...
BoxDecoration(
    gradient: gradientColors !!
        LinearGradient(
          colors: gradientColors!, // `!` only needed if `gradientColors` is not a local variable.
        ),
)

This comment mentions some other proposals in the same area.

Thanks! I've tried to find similar issues as I was nearly sure there should be already some discussion about this topic, but failed to found it :)

Feel free to close this issue in favour of #361