[Rd] "Unfelicity" :-) with edit()

François Pinard pinard at iro.umontreal.ca
Tue May 9 15:17:05 CEST 2006

[Duncan Murdoch]

>I'll fix it.

Thanks, Duncan.  While I quite understand that more serious work should 
be done within real sources files, fixing and editing is still useful 
for quick, evanescent interactive toying.

>edit() is a hack, so you should expect problems.  You're better off 
>keeping your source in an editor and using source() to get it.

This is not the first time I read such a remark.  Maybe it would be 
worth a note within ?edit.

>There is no way it could preserve the environment of a function [...]

That might be worth another note within ?edit.

Speaking of which, this "x <- edit()" usage (interactively suggested by 
fix when it fails to re-parse the result of edition) is not covered by 
?edit.  I mean that by reading ?edit, one does not get information about 
what a mere "edit()" does.  It might be useful that ?edit says a few 
words about this particular usage.

The remaining of this message quotes the original message:

[François Pinard]
>Hi, people.  This is about R 2.3.0 under Linux.

>It seems that edit() may change a function environment.  Here is 
>a transcript, more comments follow:


>function ()

>Erreur dans edit(name, file, title, editor) :
>         une erreur s'est produite à la ligne 3
>  utilisez une commande du genre
>  x <- edit()
>  pour corriger

>>f <- edit()

>function ()
><environment: base>

>The initial ``fix(f)`` called an editor, which I exited right away.  For 
>the second ``fix(f)``, I used the editor for adding a slash between 
>braces, and exited.  The French comment produced by R speaks about an 
>error at line 3 and suggests using something like ``x <- edit()`` to 
>make a correction.  On the third call to the editor, I remove the slash 
>and exit.  Now, the environment of the function became "base".

>This has unfortunate effects when editing a more substantial function, 
>because for example, "stats" or "utils" is not readily available anymore 
>after the editing.  Is it reasonable to suggest an improvement in the 
>mechanics of edit(), for alleviating this drawback ?

François Pinard   http://pinard.progiciels-bpi.ca

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