Since perl doesn't have lazy data natively this can get a little tricky and rather messy if dealing with lexicals, however ...

my $var  = q[date $date];
my $date = localtime;

print eval qq["$var"]'

__output__

date Tue Mar  9 18:11:43 2004
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But it's usually best to leave this sort of thing up to Interpolation or perhaps one of the templating modules.