problem with loadMethod for lubridate in Rscript

[mccreigh]

Compose the Rscript with file name lubridateTest.Rsh:

#! /usr/bin/RScript
lubridate::round_date(Sys.time(),'minute')

Run it:

jamesmcc@chimayo:~> ./lubridateTest.Rsh 
Error in x - eseconds(1) : could not find function "loadMethod"
Calls: <Anonymous> ... as.POSIXct -> ceiling_date -> floor_date -> update -> -
recover called non-interactively; frames dumped, use debugger() to view

This works however:

#! /usr/bin/RScript
library(lubridate)
lubridate::round_date(Sys.time(),'minute')

Run it:

jamesmcc@chimayo:~> ./lubridateTest.Rsh 
Loading required package: methods
[1] "2015-04-22 13:25:00 MDT"

I have no idea why, but it just is this way. I'm curious to know however.
Thanks,
J

[vspinu]

This applies to all S4 packages. The problem is that methods package is not attached from Rscript. This will work:

#! /usr/bin/Rscript
library(methods)
lubridate::round_date(Sys.time(),'minute')

I think there is a way around it, like explicitly calling require(methods) in evalOnLoad, but I am not sure we should bother with that. @hadley should know better what is the recommended way to deal with this issue.

[hadley]

I think this might be fixed in 3.2

[vspinu]

It's still there in today's devel but under a different form:

Error in dseconds(1) : could not find function "new"
Calls: <Anonymous> ... as.POSIXct -> ceiling_date -> floor_date -> update -> dseconds
In addition: Warning message:
no function found corresponding to methods exports from ‘lubridate’ for: ‘show’ 
Execution halted

[hadley]

Are you importing the methods package and new etc?

[vspinu]

Are you importing the methods package and new etc?

Nope. methods is in Depends and no explicit imports for new, show etc are there. I guess that was it.

[vspinu]

Ok. I have imported new and show. Now I am getting

Error in .setupMethodsTables(fdef, initialize = TRUE) : 
  trying to get slot "group" from an object of a basic class ("NULL") with no slots
Calls: <Anonymous> ... getMethodsForDispatch -> .getMethodsTable -> .setupMethodsTables

Importing the whole methods package results into:

Error in x - dseconds(1) : could not find function "loadMethod"
Calls: <Anonymous> ... as.POSIXct -> ceiling_date -> floor_date -> update -> -

Explicitly importing loadMethods doesn't help.

[hadley]

Does R CMD check give anything helpful?

[vspinu]

Does R CMD check give anything helpful?

Nope.

[hadley]

I now get

Rscript -e "lubridate::round_date(Sys.time(),'minute')"
[1] "2015-05-13 13:15:00 CDT"

I don't know how to make sure we've correctly imported every needed generic from methods though.

[vspinu]

Rscript -e "lubridate::round_date(Sys.time(),'minute')"

Hm. It works for me as well. So it was magically fixed since then.

I don't know how to make sure we've correctly imported every needed generic from methods though.

We can add this as a test to travis. So each time we rely on a method it's spotted.

[hadley]

@vspinu it's not exactly magic - I made some commits to fix it ;)

[vspinu]

Aha. I see. It's 8fa6ba3.

---

I have added this one to the tests. You might want to have a lot at it.

The call executes fine on test("path/to/lubridate") but not on check("path/to/lubridate"). I am deactivating it on Travis because of this. I also don't want to have a separate script for that because of the convenience of devtools::test. Any ideas?