R devel - Dec 2011 - Debugging namespace problems

Hi all,

I frequently find that I've failed to export something in my NAMESPACE
and hence my package doesn't work when it's imported into another
package. Does anyone have suggestion for debugging this type of
problem?  R CMD check passes without any ns related errors on both the
importee and the importer.

I've attached a reproducible example - if you install the development
version of ggplot2 (e.g. with devtools::install_github("ggplot2") the
attached package fails R CMD check with:
> ### ** Examples
>
> plot(my_plot())
Error in structure(list(data = data, layers = list(), scales = Scales$new(),  :
  attempt to apply non-function
Calls: plot ... my_plot -> ggplot -> ggplot.data.frame -> structure
Execution halted
Error: Command failed (1)

Hadley

-- 
Assistant Professor / Dobelman Family Junior Chair
Department of Statistics / Rice University
http://had.co.nz/
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I should add that I'm pretty sure this is something wrong with the
ggplot2 NAMESPACE because if I explicitly attach ggplot2 the code
works:
> library(nstest)
> my_plot()
Error in UseMethod("scale_dimension") :
  no applicable method for 'scale_dimension' applied to an object of
class "NULL"
> library(ggplot2)
> my_plot()
# Plot appears.

Hadley

On Fri, Dec 23, 2011 at 1:50 PM, Hadley Wickham <hadley at rice.edu>
wrote:
> Hi all,
>
> I frequently find that I've failed to export something in my NAMESPACE
> and hence my package doesn't work when it's imported into another
> package. Does anyone have suggestion for debugging this type of
> problem? ?R CMD check passes without any ns related errors on both the
> importee and the importer.
>
> I've attached a reproducible example - if you install the development
> version of ggplot2 (e.g. with devtools::install_github("ggplot2")
the
> attached package fails R CMD check with:
>
>> ### ** Examples
>>
>> plot(my_plot())
> Error in structure(list(data = data, layers = list(), scales =
Scales$new(), ?:
> ?attempt to apply non-function
> Calls: plot ... my_plot -> ggplot -> ggplot.data.frame ->
structure
> Execution halted
> Error: Command failed (1)
>
> Hadley
>
> --
> Assistant Professor / Dobelman Family Junior Chair
> Department of Statistics / Rice University
> http://had.co.nz/


-- 
Assistant Professor / Dobelman Family Junior Chair
Department of Statistics / Rice University
http://had.co.nz/