plumber() and Plumber$new() will read source file as UTF-8 encoded

[shrektan]

Related to #296

DESCRIPTION

R uses the encoding "unknown" or "native" when reading text files by default. However, the fact that the default encoding varies (not UTF-8) on Windows, leads to a big headache for our multiple-bytes charset users on Windows, which is we have to store the source file as the native encoding in order to use plumber.

Thanks to the great work of RStudio (especially, @yihui), the common practice of handling this issue is to read the file as UTF-8 encoding by default(may provide a param "encoding" allowing users to change) and this PR is going to address this.

WHAT THIS PR DOES?

• add the new param encoding for plumber() and Plumber$new()
• enable the UTF-8 as the default

As mentioned in #296, there's another issue that the function input should be marked as UTF-8, which I would like file another PR after this being merged.

Thanks.

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[yihui]

YES! Use UTF-8, or we can't be friends.

Perhaps in knitr 2.0 and rmarkdown 2.0, I'll just remove the encoding arguments, and force UTF-8 like what Pandoc has been doing for years, which is something I have envied for long.

[schloerke]

@yihui Do you think it's a good idea remove the argument and just force UTF-8?

[shrektan]

At least, it’s a good idea to me, actually. :P

[yihui]

@schloerke Yes. That is what I have been doing in bookdown (since 2016) and blogdown (2017). In future packages, I'll always do this. The encoding argument brings enormous pain to developers, whereas it only bugs users a tiny bit when they are asked to save a text file in UTF-8 (they can set this as the default in RStudio).

[schloerke]

@shrektan Mind removing it from the args and adding it as a global package variable w/ comment to this PR? (Feel free to copy from below)

# Hard code UTF-8 file encoding
# Removes encoding headache at minor cost of setting encoding in editor
# https://github.com/trestletech/plumber/pull/312
utf8Encoding <- "UTF-8"


plumb <- function(file, dir = "."){
# ...
x <- source(entrypoint, encoding = utf8Encoding)
# etc...
}

[shrektan]

@schloerke I have removed it.

[schloerke]

See comments. Should be last round of review

Thank you for the test file!

[shrektan]

@schloerke I've made the changes you requested and add a NEWS file (I made a forced-push in order to have a clean history).

Can it be merged? It's very inconvenient to maintain/edit the file as encoding other than UTF-8. Moreover, it's consistent with shiny, which forces the UTF-8 encoding in the very early stage.

shiny 0.10.1

Added Unicode support for Windows. Shiny apps running on Windows must use the UTF-8 encoding for ui.R and server.R (also the optional global.R) if they contain non-ASCII characters. See this article for details and examples: http://shiny.rstudio.com/gallery/unicode-characters.html (#516)

In addition, there's a minor issue about using utf8Encoding to represent the literal string "UTF-8" (see the quote below). Although I made the change, I don't support it because it's not a "magic" value in R. As you can see in other packages like shiny or in pkgload, they almost always are written directly.

@shrektan Mind removing it from the args and adding it as a global package variable w/ comment to this PR? (Feel free to copy from below)

# Hard code UTF-8 file encoding
# Removes encoding headache at minor cost of setting encoding in editor
# https://github.com/trestletech/plumber/pull/312
utf8Encoding <- "UTF-8"


plumb <- function(file, dir = "."){
# ...
x <- source(entrypoint, encoding = utf8Encoding)
# etc...
}