R devel - Aug 2012 - Suggestion: Change default to download.file(..., mode="wb") ...instead of mode="w" with some bells and whistles

Hi,

I keep seeing the problem where people are download binary files as
text (mode="w") when using R's download.file() for FTP/HTTP
downloads.
 It often results in unnecessary troubleshooting until one concludes
that the downloaded file has been corrupted due to (what I think is)
translated newlines.  Search the r-help mailing list and you'll find
other examples of this.  This may or may not only be a problem for
Windows users.

I'd like to suggest to change the default of argument 'mode' of
download.file() to be mode="wb".  The "default" is current
mode="w"
except when argument 'mode' is missing (not explicitly given),
download.file() tries to be helpful by forcing 'mode' to be
"wb" for
certain filename extensions.  NB: help("download.file",
package="utils") has a paragraph on all this.  BTW, the latter seems
to be done in a case-sensitive way, such that *.zip and *.ZIP will
have different behaviors.

Wouldn't it just be safer to change the default to mode="wb"? 
...or
are there use cases that I'm overseeing - is anyone out there
intentionally using the "text" transfer mode?

/Henrik

I would second this suggestion.

On Wed, Aug 29, 2012 at 12:27 PM, Henrik Bengtsson
<hb@biostat.ucsf.edu>wrote:
> Hi,
>
> I keep seeing the problem where people are download binary files as
> text (mode="w") when using R's download.file() for FTP/HTTP
downloads.
>  It often results in unnecessary troubleshooting until one concludes
> that the downloaded file has been corrupted due to (what I think is)
> translated newlines.  Search the r-help mailing list and you'll find
> other examples of this.  This may or may not only be a problem for
> Windows users.
>
> I'd like to suggest to change the default of argument 'mode' of
> download.file() to be mode="wb".  The "default" is
current mode="w"
> except when argument 'mode' is missing (not explicitly given),
> download.file() tries to be helpful by forcing 'mode' to be
"wb" for
> certain filename extensions.  NB: help("download.file",
> package="utils") has a paragraph on all this.  BTW, the latter
seems
> to be done in a case-sensitive way, such that *.zip and *.ZIP will
> have different behaviors.
>
> Wouldn't it just be safer to change the default to mode="wb"?
...or
> are there use cases that I'm overseeing - is anyone out there
> intentionally using the "text" transfer mode?
>
> /Henrik
>
> ______________________________________________
> R-devel@r-project.org mailing list
> https://stat.ethz.ch/mailman/listinfo/r-devel
>
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