[qmtest] Specifying arguments in derived test classes

[Mark Mitchell]

--On Monday, April 15, 2002 07:33:05 PM +0400 Vladimir Prus 
<ghost at cs.msu.su> wrote:

> Mark Mitchell wrote:
>> <ghost at cs.msu.su> wrote:
>> > Hi,
>> > I'm trying to create a test class that would derive from
>> > python.ExecTest and  change it a little. In particular, I want to get
>> > rid of 'expession' argument.  I'm trying the following:
>
>> There's no easy way to do this.
>>
>> The plan is to add "computed arguments" which would solve this problem.
>> For the time being, you have no real choice but to create a whole new
>> class.
>>
>> (At one point, it was possible to do approximately what you wanted;
>> each class could completely override "arguments".  We decided this was
>> a bad design since that meant that derived classes had to explicitly
>> list the arguments from the base classes, and there was no guarantee
>> that the "is-a" relationship would be preserved.)
>
> Actually, I don't think that there's the need to explicitly list
> arguments.  Why the following is not appropriate:
>
> class Test(python.ExecTest):
>
> 	arguments = [ ...... ] + python.ExecTest.arguments
>
> 	..........

Yes, that's exactly how it used to work.  We decided that a better
approach would be to allow derived classes to indicate that some
arguments could be computed by base classes instead -- but that has
not yet been implemented.

Another approach would be to make your new class a base class, and
derived ExecTest from that.

--
Mark Mitchell                   mark at codesourcery.com
CodeSourcery, LLC               http://www.codesourcery.com