created a eng_r function which exposes the R engine

[abhsarma]

I created a separate engine for handling R code blocks, and exported it to make it accessible to users. This was useful in the implementation of our engine --- we are creating a package which allows end-users to declare multiverse analyses (multiple reasonable alternative statistical analysis pipelines) in a flexible and concise manner. Thus, our implementation resulted in a syntax which is not strictly R, but is processed into (multiple sets of) valid R syntax. We want to execute these generated R syntax using knitr to create rendered documents, which is not possible as current implementation does not expose this to the developer.

It can be useful to extend the R syntax --- developers can create custom engines which allows end-users to write commands/syntax which is not strictly in R but can then be processed into R output if necessary.

Example:

r_code <- process_code(options$code) # processes code which is not R to valid R syntax

eng_r(r_code) # outputs which have knitr formatting

[CLAassistant]

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[yihui]

It sounds good to me to factor out the R engine. I just want to make a slight modification, i.e., register this engine via knit_engine$set(R = eng_r) in engine.R. Then you don't need to export the function eng_r, but can access it via knit_engine$get('R'). Would that be okay to you?

BTW, if you use RStudio, please use Ctrl + Shift + B to generate the Rd files. Or just leave out changes in Rd. Thanks!

[abhsarma]

Thanks for bringing that up. I've changed things so that eng_r is no longer exported and it works like you said. I also reset the head and tried to leave out changes in the Rd files, but I am not sure why there are still conflicts. Please let me know if I can do anything else

[yihui]

Looks perfect now. Thanks!

[abhsarma]

Awesome thank you!

[cderv]

That is awesome @abhsarma !
it was something I had in mind for a long time ! IMO it simplifies the reading / understanding of code and will allow to do more extension of R engine behavior !

Thank you for this !