On 12/10/2011 3:57 PM, Greg Snow wrote:
If you want to hide some code from accidental or casual sight then I have had
some success with adding something like this to the .R file for a package (the
petals function in TeachingDemos in this case):
.onAttach<- function(...) {
petals<- petals
attr(petals,'source')<- "Don't Cheat!"
assign('petals',petals,'package:TeachingDemos')
}
Though that would only slow an experienced R programmer down by maybe 10
seconds if they really wanted to see the code, it might take an intermediate
level R programmer a whole minute to figure out how to work around this. But
it would prevent an honest user that knew of a license or agreement to not look
at the code from accidentally seeing what they agreed not to.
You should be aware that this will no longer work in R 2.14.0, which
finally drops the "source" attribute. This would achieve a similar effect:
srcfile <- srcfilecopy("", "Don't cheat")
srcref <- srcref(srcfile, c(1,1,1,12))
attr(petals, "srcref") <- srcref
Duncan Murdoch
You could also include something in the code that checked the attribute and
stopped working if it was changed or somehow notified you of the change.
Combining this with the license agreements as others have said might give you
additional recourse.
You can see the petals.R file in the TeachingDemos package on R-forge for
another example of obfuscating (bleaching) a key piece of code. Combining the
2 might slow down an expert by a whole 30 seconds, but at least they would not
be able to claim that they accidentally saw the code.
Whether this violates the spirit of R licensing or not is another issue.
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