yogthos
false values turn into nil
Passing in something as a boolean false seems to turn into a nil. So:
(println (render "Blah {{boo|str}}" {:boo false}))
prints "Blah" instead of "Blah false" as expected when doing (str false) in regular clojure.
That's because lookup in the context map that results in a false is treated as absence of value, so it never gets to the filter. Changing this would affect the existing API however, so I'd be hesitant to do that. A workaround would be to stringify false values before passing them to render.
Whoops, it looks like this tripped us up in our API documentation generator, which relies on some nested Selmer templates and custom tags, as well. I think your suggested workaround may work for us, though, because I am tracking separately whether the value being rendered is supposed to be a string literal or not.
Is this going to be fixed at some point? We just found the bug on production and were kind of surprised how it works. (str value) of course helps for now.
My only hesitation here is that it would be a breaking API change for the library. Perhaps one approach would be to make this a configuration option.
Personally, I'd rev the major version at some point and fix this. I get that breaking changes are a big deal, but I have trouble believing that anyone wants this behavior. It seems like leaving a landmine for new users in perpetuity is the greater evil compared to a breaking change properly labelled in a major release.
This bit me in a real-world project and caused, what was from my perspective, a rendering bug in the resulting application that was present for several releases before being found by internal testing and only then did we find this bug report.
It sounds like the consensus here is that it would be a desirable change. I'm open to a PR for this. The breaking change could be noted in the change log. I think that would be adequate.