Richard Williams ([email protected]) asked about -adoupdate-
and ado-files downloaded from SSC for Stata 11 vs. Stata 10:
On Mon, Jun 29, 2009 at 04:06:25PM -0400, Richard Williams wrote:
> I wonder if -adoupdate- becomes potentially dangerous for people who
> don't update their Stata version. Suppose you have Stata 10, and you
> have a routine you downloaded from SSC that works with Stata
> 10. Then, the author updates the program so it requires Stata
> 11. When you run -adoupdate-, won't the version that works with
> Stata 10 get overwritten by the version that requires Stata 11?
>
> Most authors will probably keep a renamed version of the earlier
> program available, but it might be nice if adoupdate warned you when
> you were about to update to a program you can't run.
It is true that -adoupdate- will seek out the newest update to
a given package which has been -net install-ed, no matter what
the version number is in the ado-files in that package. So, Richard
is right to be thinking about this.
It would be possible to modify -adoupdate- to take note of a version
comment within the text of the package file it is checking, but even
better than that would be for this to be a feature understood by
Stata's -net- command. It is too late for such a feature to be
added to Stata 11, but we may add it in the future.
However, Richard's email leads me to want to talk about version
control in user-written programs. Over the years, I have seen
authors of user-written programs put out a command named, say, 'x',
which runs under Stata 11, and put out another command, say, 'x_10',
which is known to run under an earlier version of Stata. End-users must
decide whether to install 'x.ado' or 'x_10.ado' and must remember to
type -x- or -x_10-.
There is a simple, and better, solution, for authors of user-written
programs who wish to implement version control in the way developers at
StataCorp would do so. This solution lets users of Stata 11 type
-x- to access the Stata 11 version of x.ado, and it also lets users of
Stata 10 type -x- (NOT -x_10-) to access the Stata 10 version.
The author of the program still creates x.ado and x_10.ado, but
x.ado has a few lines of code in it which allow it to be smart
so it can call the older x_10.ado if a user is running under
version 10:
----x.ado--------------------------------------
program x
if _caller() < 11 {
x_10 `0'
exit
}
version 11
// the code for the Stata 11 version
// of 'x' goes here
end
----x.ado--------------------------------------
----x_10.ado-----------------------------------
program x_10
version 10
// the code for the Stata 10 version
// of 'x' goes here
end
----x_10.ado-----------------------------------
This takes no more work for an author who was going to create
both x.ado and x_10.ado anyway, but it is cleaner for end-users.
It also means that even if a user installs an updated version
of the 'x' package, as long as they have used version control in
their own do- and ado-files, the appropriate version of -x-
will be executed.
--Alan
([email protected])
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