don't make default_type global

[jonathanong]

i'd prefer when a lookup fails, it returns something falsey like false instead of application/octet-stream. i would love to set the default type to something, but since it's global, i'm afraid it'll ruin other modules since this repo is used a lot.

aside from doing a major version bump, how about adding a second "default" option to the methods?

mime.lookup(file, false)

would return a valid mime type or false

[broofa]

Old, but relevant Mozilla discussion about default types: https://issues.apache.org/bugzilla/show_bug.cgi?id=13986 (just dropping this here for reference. not expressing any opinion on how it may or may not apply here.)

[broofa]

You make a good point about how the 'global' nature of default_type is problematic. Will have to digest this. Could you (in the mean time) just check (mime.lookup('foo') === mime.default_type) for now? I know it's less than ideal. :-/

[jonathanong]

Yeah not a big deal. Thanks!

[andrewrk]

mime.lookup('foo') === mime.default_type is not correct and can lead to subtle bugs. What if some other module sets default_type to image/png? Now all my PNGs have a bogus mime type.

There's an easy workaround though, just make the fallback parameter to lookup public instead of private API. E.g. advertise in the README that it's OK to use.

[jons]

when in doubt, do what the standard says, or in this case, do what the most common tools do.

http://linux.die.net/man/1/file
http://linux.die.net/man/5/magic

[broofa]

See #139 (plan is to have v2 return null instead of default type.)