Ability to step through expressions

[apalskoi]

This is a great tool! I've been toying with a similar technology, generating nested functions with callbacks even before generators, but run into an issue with expressions that do not have a return type.

Does debugjs have an ability to step through complex expressions? E.g. in this example

  if(param>2 
     && param<5) {
    alert(param);
  }

From a test on debugjs.com it looks like the entire if() condition is checked in a single step.

[amasad]

right now it's statement based https://github.com/amasad/debugjs/blob/master/lib/transform.js#L147 But I don't think it will take too much effort to make it expression based, however, performance would be the issue. The more 'steps' we add the less performant it is.

[apalskoi]

It should probably be configurable or even better - have an ability to dynamically drill down into a specific statement if it was stopped on via a breakpoint or debugger step. I.e. normally for performance reasons it would operate on per-statement level, but if somebody stops on a given statement, then you switch to expression-based mode and allow to step into the statement.

I guess it's not that easy to do since the instrumented code is prepared before the debugger starts and it may be hard to regenerate more detailed version for a specific statement and inject it on the fly? Would be cool though

[amasad]

yeah it'd be great to have both. Maybe it's possible. Feel free to hack on it.

On Fri, May 2, 2014 at 3:15 PM, apalskoi [email protected] wrote:

It should probably be configurable or even better - have an ability to dynamically drill down into a specific statement if it was stopped on via a breakpoint or debugger step. I.e. normally for performance reasons it would operate on per-statement level, but if somebody stops on a given statement, then you switch to expression-based mode and allow to step into the statement.

I guess it's not that easy to do since the instrumented code is prepared before the debugger starts and it may be hard to regenerate more detailed version for a specific statement and inject it on the fly? Would be cool though

— Reply to this email directly or view it on GitHubhttps://github.com/amasad/debugjs/issues/7#issuecomment-42067577 .

[apalskoi]

Thanks! I'll try researching it further once I get a chance. For now I am using a little home-grown debugger library in my project but your tool is much more powerful. Thanks again for creating it!

[amasad]

you got it. Do you have a link to your library?

[apalskoi]

It's a part of a larger project that is work in progress. I only have a link to the future users guide - https://github.com/GraspIO/docs-users-guide/blob/master/Editor/Panels.md#test-panel. It describes debugger for a model-driven code generator, but if the target code is Javascript, you can run/debug the code itself and it will highlight corresponding parts of the original model.

[amasad]

Looks cool! And you were thinking of using debugjs for this project?

[apalskoi]

Yes, I would love to use it and also explore the ideas from Learnable Programming but take it from the coding-land to something that is easier for regular people to understand - forms, diagrams, etc.

Here is a simple example of a graphical formula editor with code generation/execution - http://www.grasp.io/workbench?repositoryID=publicExamples&anonymous=true#!/exampleFormula (open the "testing tab" and try running it twice - first run generates the code and second run steps through it, maintaining the link to the original model)