Investigate consequences of empty flags

[psolymos]

E.g. one can type it incorrectly: Rscript index.R -- test instead of Rscript index.R --test.

Is this somehow preventable?

• Should we remove leading spaces for flags? -- no b/c that would leave the script invalid, and we cannot differentiate key from value
• Should this be an error? -- YES
• Should it be silently ignored? -- no b/c that would leave the script invalid

[psolymos]

Using Gitpod, we can verify that an empty flag is dangerous. --value ok works fine:

Rscript test.R --value ok

Loading required package: utils
Tracing function "install.packages" in package "utils"
List of 6
 $ trials     : int 5
 $ dataset    : chr "demo-data.csv"
 $ cores      : int 1
 $ user       :List of 1
  ..$ name: chr "demo"
 $ description: chr "This is a multi line\ndescription."
 $ value      : chr "ok"
 - attr(*, "trace")=List of 2
  ..$ kind : chr "merged"
  ..$ value:List of 2
  .. ..$ :List of 2
  .. .. ..$ kind : chr "file"
  .. .. ..$ value: chr "/workspace/rconfig/inst/examples/rconfig.yml"
  .. ..$ :List of 2
  .. .. ..$ kind : chr "args"
  .. .. ..$ value: chr "--value ok"
 - attr(*, "class")= chr "rconfig"

--value ok leaves a trace but sets no value:

Rscript test.R -- value ok

Loading required package: utils
Tracing function "install.packages" in package "utils"
List of 5
 $ trials     : int 5
 $ dataset    : chr "demo-data.csv"
 $ cores      : int 1
 $ user       :List of 1
  ..$ name: chr "demo"
 $ description: chr "This is a multi line\ndescription."
 - attr(*, "trace")=List of 2
  ..$ kind : chr "merged"
  ..$ value:List of 2
  .. ..$ :List of 2
  .. .. ..$ kind : chr "file"
  .. .. ..$ value: chr "/workspace/rconfig/inst/examples/rconfig.yml"
  .. ..$ :List of 2
  .. .. ..$ kind : chr "args"
  .. .. ..$ value: chr "-- value ok"
 - attr(*, "class")= chr "rconfig"