Cap Sphinx version to avoid issue with newer version

[dmey]

Temporary workaround for:

Exception occurred:
  File "/home/travis/virtualenv/python3.6.7/lib/python3.6/site-packages/sphinx/application.py", line 1069, in add_source_parser
    self.registry.add_source_parser(*args, **kwargs)
TypeError: add_source_parser() takes 2 positional arguments but 3 were given

[dmey]

@hongyuanjia I am getting an issue with R on the CI (please see https://travis-ci.com/github/psychrometrics/psychrolib/jobs/316453651#L4373-L4376). Do you know how to fix this?

[hongyuanjia]

This is caused that we did not commit the NAMESPACE file, which makes Rcpp confused and it thinks that it was not inside an R package. See r-lib/devtools#1599 and https://github.com/RcppCore/Rcpp/blob/a83163943bcbbafc91f66cac72ff8f7bab790730/R/Attributes.R#L425-L430.

I am not sure why NAMESPACE was not automatically generated by devtools::document() and I cannot reproduce this error on local repo.

[dmey]

It looks like the real reason for the failure is actually due to ‘shiny’’: https://travis-ci.com/github/psychrometrics/psychrolib/jobs/316453651#L3762. Great error reporting in R, I am surprised that builds continue even when individual packages fail to build.

[hongyuanjia]

No. I don't think so. The reason htmlwidgets package is to be installed is that we specify dependencies = TRUE when installing devtools, which will also install packages listed in Suggests in devtools' DESCRIPTION. Those packages are not directly required by the core functionalities of devtools and are mainly used for testing devtools itself. It is safe to remove them for our purpose. And the reason why shiny is failed to install and does not cause the build to fail is that shiny is only listed as Enhances in htmlwidgets and will not be caught by the option dependencies = TRUE, which equals to c("Depends", "Imports", "LinkingTo", "Suggests"). Thus failed to find shiny package will not cause htmlwidgets package to fail to install.

The root of the failure still lies in missing NAMESPACE file before devtools::document(). After manually creating NAMESPACE, the error is gone.

[hongyuanjia]

Also since we did not commit RcppExports.R, when fresh installing, devtools::document() sometimes will not run Rcpp::compileAttributes() to automatically create it. It is safe to call it after devtools::document().

[hongyuanjia]

See PR #58