manageR imports layer with improper names then bugs

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The rules for valid layer names in qgis is not the same as the rule of
standard accepted objects in R.
Consequently, it is possible to import into R objects that don't have
"valid" names.
For instance, a layer with a dash ("-") in the name, or a name starting
with a numeric can be imported but is then very hard to manage with R.

What steps will reproduce the problem?
1. create a layer named "123test" or "my-test" in qgis
2. import it in ManageR
3. Select any tool in "Analysis" menu. You get a long error message, part
of it is:
nexpected symbol in "123test"

What is the expected output?
three options:
 1) try to manage those layers
for instance, rm(123test) will give an error, but rm("123test") works
I doubt it is possible to find workarounds for all function. 

2) give an error message when trying to import such a layer

3) when trying to import such a layer, let the user give a different object
name, telling which rules it must obey.


What version of the product are you using? On what operating system?
Qgis 1.4.0
OS: kubuntu 9.10
Python version:
2.6.4 (r264:75706, Dec  7 2009, 18:59:58) 
R version 2.10.0 (2009-10-26)

Original issue reported on code.google.com by [email protected] on 14 Apr 2010 at 9:26