If a Views Contextual Filter using PHP code doesn't resolve, can I make Views "Display all results"

Question

Situation:

1. Contextual filter "Has taxonomy term by ID"
2. Filter is set to "Provide default value" > "Type: PHP Code"
3. The PHP code resolves in most cases, but on some pages it shouldn't. In those cases I'd like to do what Views does when you choose the "Display all results for the specified field" option.

Is there something my PHP code can pass back to Views that will cause it to display all results?

(Or even 'Display contents of "No results found"' because then I could use a View inside there)

Config: Views 3, D7

Answer 1

when you want to show all then

return "all";

;)