Thanks for your question ;-). There's nothing wrong with your quest, and I deeply appreciate your curiosity. ;D.

The probelm with my current template parser is that the I use standard Perl eval() for expressions at the moment and _only_ if you set a variable via <CFSET> tag. Setting a variable via parameter list (the test page) is equivalent to this assignment in perl:

$foo_var = 'foobar';
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If done via CFSET however, the expression should be evaluated, since that's how CFSET handler class was coded to perform.
Whilst Perl eval()'s enough for testing, there'll have to be a CFML compatible eval() in place in order for this to work well. In many respects Perl eval() would be similar to CFML eval.

"There is no system but GNU, and Linux is one of its kernels." -- Confession of Faith