On 2009-12-02 16:31, Peng Yu wrote:
On Tue, Dec 1, 2009 at 11:27 PM, Sharpie <ch...@sharpsteen.net> wrote:
Peng Yu wrote:
Then I try the package 'try.package' in an R session. I'm wondering
why neither 'my_test_f' and 'try.package::my_test_f' work.
The error message you got below clearly explains this-- you did not export
my_test_f in your NAMESPACE file. To access unexported functions, you must
use the ':::' operator:
try.package:::my_test_f()
Peng Yu wrote:
Why 'my_test_g' can be accessed with 'try.package::' and without
'try.package::'?
Because you exported it in the NAMESPACE file.
Peng Yu wrote:
Is there a way to make 'my_test_g' accessible only by specifying the
namespace 'try.package::'?
No.
The purpose of the '::' operator is for those cases where multiple packages
are loaded that each export a function with the same name. This is known as
"masking" and the last loaded package will contribute the dominant
function-- i.e. the function the gets called when the user types
"functionName()" and not "packageName::functionName()". The "::" operator
allows the selection of functions that are masked by the dominant function.
If you really want to conceal a function from user-level code, don't export
it and it will only be accessible via the ":::" operator.
Is there a way to list all the functions in a namespace? I tried the
following one, but it is not working.
showMethods(where=getNamespace('try.package'))
No applicable functions
You're almost there, and the above approach *is* working but only for S4
methods. Try
showMethods(where = e <- getNamespace('stats4'))
I don't think there's a direct analogue for S3, but it that case you only do
ls(e)
HTH,
Henric
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