[cmake-developers] conditionals in generator expressions

[Brad King]

On 09/12/2012 11:36 AM, Stephen Kelly wrote:
> I've force-pushed the generator-expression-refactor branch to my gitorious 
> clone. 

Great progress!

One thing that bothers me about the current design is that the
cmGeneratorExpression instances now have more states.  This
pattern appears everywhere they're used now:

+      ge.Parse(*cli);
+      ge.Evaluate(this->Makefile, 0, true);

If one forgets the first line there will be runtime errors.  Can you
split the class up so that ge.Parse() returns a "compiled" generator
expression as a separate object that provides the Evaluate() interface?


This documentation needs clarification:

+  "This generator expression can only be evaluated if it is used in "   \
+  "target scope, such as a target property.\n"                          \

All expressions are evaluated in "target scope" when used to generate
build rules.  Only expressions used in add_test calls are evaluated
without a "this" target.  Please refactor the way the documentation of
generator expressions is produced so that the copy that appears in the
docs of add_test does not mention expressions it can't use.

> The unit tests pass for me, and I think it's ready to merge to next. I don't 
> remember the magic git log command to check the style for text width though?

 git log origin/master.. --pickaxe-regex -S'.{80}'

> The next thing I want to do is to see if I can make full use of 
> cmGeneratorTarget and use const proactively while doing so, to make the code 
> more clear. I'm not 100% certain that's possible, but it's the next goal I 
> have. Any comments on that?

That would be a really great example of splitting configure-time
constructs from generate-time constructs.

-Brad