# Is possible keep typedef info when compile to cs target or js?

**URL:** https://community.haxe.org/t/is-possible-keep-typedef-info-when-compile-to-cs-target-or-js/2109
**Category:** Haxe
**Created:** [October 30, 2019, 9:16am UTC](https://community.haxe.org/t/is-possible-keep-typedef-info-when-compile-to-cs-target-or-js/2109 "2019-10-30T09:16:32Z")
**Posts on this page:** 1
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### Author: ![vlado](https://community.haxe.org/user_avatar/community.haxe.org/vlado/32/1074_2.png) [@vlado](https://community.haxe.org/u/vlado)
#### Post date: [October 30, 2019, 9:29pm UTC](https://community.haxe.org/t/is-possible-keep-typedef-info-when-compile-to-cs-target-or-js/2109/4 "2019-10-30T21:29:58Z")

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For the sake of it, you could mimic the conciseness of a typedef by defining a minimal class with just variables in it (let’s call it TypeDefLike). It would extend an empty class (let’s call it TDL) which is marked with an @:autoBuild in order for all it’s subclasses (in our case TypeDefLike) to be run through a macro.

In the macro you get all variable fields defined in TypeDefLike and make them public. Then you generate a constructor field taking a parameter for each variable and storing the values in its own properties. Lastly you mark the class with @:rtti and @:structInit metadata.

This way you can create an instance of the class the same way you instantiate a typedef and can access its type information at runtime. The drawbacks are that

- you have some compile-time overhead (although negligible)
- the class definition isn’t as concise as a typedef
- you have some black magic going on in the code that’s not obvious

There’s a plus side too: you can provide default values for the variables, which you can’t do with a typedef.

Here’s an example [Try Haxe !](https://try.haxe.org/#B1890)  
It needs some modifications in order to compile as [try.haxe.org](http://try.haxe.org) disallows mentioning macro-related stuff.

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