hg: unknown command 'extdiff''

I can't figure out why my extdiff extension is not working for Mercurial (on a Mac).

this is what my .hgrc file looks like:

[extensions]
fetch=
hgext.extdiff =

[extdiff]
cmd.kdiff3 =

[ui]
merge=kdiff3

[merge-tools]
kdiff3.executable=/Applications/kdiff3.app/Contents/MacOS/kdiff3
kdiff3.args = $base $local $other -o $output

and yet kdiff3 is recognized as a merge tool.. and can be run from the cmd line like "kdiff3". but what i'd like to do is use kdiff3 as a gui tool for comparing diff files.

like this: hg extdiff -p kdiff3

this seems like the best way of using kdiff3 as a popup gui when using Mercurial.

I am new to this and am not sure if I am doing it right.

Thanks...!

By the way, when I try to run 'hg extdiff'

I get:

 hg: unknown command 'extdiff'
'extdiff' is provided by the following extension:
extdiff  command to allow external programs to compare revisions
use "hg help extensions" for information on enabling extensions

(even though it is in .hgrc)

Please note that merge-tool and external diff are different tools for different tasks. For example you can use fmdiff script to use FileMerge for diff and k3diff for merge-tool:

Your .hgrc should be:

[extensions]
# enable external diff program
extdiff =

[extdiff]
cmd.opendiff = fmdiff
opts.opendiff =

[merge-tools]
# Override stock tool location
kdiff3.executable = /Applications/kdiff3.app/Contents/MacOS/kdiff3
# Specify command line
kdiff3.args = $base $local $other -o $output
# Give higher priority
kdiff3.priority = 1

Now you can use

hg opendiff myfile.ext

Please note that 'opendiff' is a custom wrapper name, so you can change it to your likes but it cannot be one of already reserver names.