Cannot access var defined in multilayer imported file - dart

Question

Say i got 3 dart scripts in the same folder.
// a.dart
import 'b.dart';
void main(){
print(foo);
}
// b.dart
import 'c.dart';
// c.dart
var foo = 1;
and I got Cannot resolve 'foo' in a.dart

Answer 1

Import doesn't automatically reexport.
You can use one of these variants:
// b.dart
import 'c.dart';
export 'c.dart';
// foo is available in b.dart and a.dart
or
// b.dart
export 'c.dart';
// foo is not available in b.dart but in a.dart
This is the same as my answer to How can I import all files in a folder? was about ;-)

Answer 2

A few alternate options.
Option 1
Solely use import statements and reference the actually files you need. For example:
// a.dart
import 'b.dart';
import 'c.dart';
void main(){
print(foo);
print(bar);
}
// b.dart
import 'c.dart';
var bar = foo + 1;
// c.dart
var foo = 1;
This doesn't allow for inherited imports, but if you follow this pattern throughout your app, your dependencies are very easy to see (they won't be hidden in another file).
Option 2
Don't use imports, but rather just make everything part of the same library.
// a.dart
library myLib;
part 'b.dart';
part 'c.dart';
void main(){
print(foo);
print(bar);
}
// b.dart
part of myLib;
var bar = foo + 1;
// c.dart
part of myLib;
var foo = 1;
This option works well if your application isn't too large and all your classes and global variables have unique names (that is to say you don't nee namespacing). You can also implement this pattern into a small subsection of your applicaiton rather than the whole thing.