wix: setting multiple value depending on a specific condition - properties

Question

I've got different installation modes. Depending on the parameters I do things like:
<Property Id="PROP1" Value="Value1" />
<SetProperty Id="PROP1" Before="CostFinalize" Sequence="execute" Value="Value2"></SetProperty>
The problem is that I've got more than 2 options, when I'm adding them I'm getting.
Duplicate symbol 'CustomAction:SetPROP1' found.
Is there a way to have some sort of switch statement or how do you handle multiple conditionals?
Another trouble is, I've got multiple variables set depending on the value (about 10 right now) and it's very cumbersome to list them all with absolutely the same code
<SetProperty Id="PROP2" Before="CostFinalize" Sequence="execute" Value="Value2"></SetProperty>
<SetProperty Id="PROP3" Before="CostFinalize" Sequence="execute" Value="Value3"></SetProperty>
etc
Is there any way to make it like:
<Condition val="...">
<setProperty.../>
<setProperty.../>
<setProperty.../>
</Condition>
Thanks!

Answer 1

First of all, try to re-think the architecture of your installation program. Is it really necessary to set all those properties based on the same condition? Or maybe it's better to "condition"-ize the appropriate features and components in a more plain way?
Let's get back to the technical side of your question. The SetProperty element is just a shortcut which is "all-in-one" solution for defining a custom action which sets a property and scheduling it appropriately. It is true that you can't use it to set the same property to different value, because there's no ID attribute of the SetProperty element itself.
Instead, use the good old style of defining a custom action and scheduling it manually:
<CustomAction Id="SetProp11" Property="PROP1" Value="Value1" />
<CustomAction Id="SetProp12" Property="PROP1" Value="Value2" />
...
<InstallExecuteSequence>
<Custom Action="SetProp11" After="...">your condition here</Custom>
<Custom Action="SetProp12" After="...">your condition here</Custom>
...
</InstallExecuteSequence>
This definitely adds extra typing work and makes your code less readable, but this way you can work your problem around. However, let me emphasize once again - the fact that you have to invent workarounds means that the code starts to smell and it might make sense to re-think it through.
And I'm not aware about the way to set a number of properties in a bunch, like in switch statement. Alternatively, technically you can create a e.g. C# custom action and let it do the job for all the properties at once.
Hope this helps.