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Non-virtual, non-comment "end tags" #34749

StokeMasterJack opened this Issue Oct 10, 2018 · 0 comments


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StokeMasterJack commented Oct 10, 2018

This is a Dart feature, but would be mostly applicable to Flutter. It would also be useful for other frameworks where one is building deeply nested trees in dart code.

Instead of this:

  onDeal: onDeal,
  onHit: onHit,
  onStay: onStay,
) //ButtonsView 

I propose this:

  onDeal: onDeal,
  onHit: onHit,
  onStay: onStay,

Note the )ButtonsView. This what I am calling an end tag, for lack of a better name.

These end tags would be easy to read by humans. And a parser would just replace the ")ButtonsView" with ")".


  • Deeply nested constructor trees (or function call trees) will be easier to read
  • IDE and Dart Analyzer can provide more useful assistance
  • End tags are visible outside of IDE. i.e. code in an email, blog post or github
  • This is not a new concept. Visual Basic had end tags for certain statements (End If). And of course XML has this.
  • This feature may satisfy those pushing for JSX-like syntax.

Other points

  • I would make it optional by default for backward compatibility.
  • Default dartfmt behavior: automatically add the end tag any time the open and close parentheses are not on the same line. And omit it if they are on the same line.
  • It could be configured in analysis_options.yaml to cause a warning or error if end tags (non-same-line) are missing.
  • It doesn't have to be exactly this syntax. For example, you could use: /ButtonsView or </ButtonsView>. But I like )ButtonsView because it is clear that the end tag is ending an arg list.
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