Proportion of valid programs view of Solomonoff induction

Proportion of valid programs view of Solomonoff induction is one of several ways of viewing the deterministic variant of Solomonoff induction. This view roughly says that to get the prior probability of seeing some output string $x$, one should take all programs in some relevant class and find the fraction of programs that output string $x$. For example, if we consider 500 programs in our class and 10 of them output $x$, the prior probability of seeing $x$ is 10/500 = 1/50.

The terminology "proportion of valid programs view" is not standard in the literature; this "view" does not seem to have a name.