Question

Is it possible to modify the behavior of a core Mercurial command (e.g. hg commit or hg status) by creating an extension?

For example, would it be possible to modify hg commit to ask the user to enter an issue tracking ID?

I understand that hook scripts could be used, but such scripts are not distributed via hg pull and need to be configured for every repository used.

Answer 1

Answering my own question

The Mercurial API provides the extensions.wrapcommand(table, command, wrapper) method which seems to provide the desired feature.

From the source code:

Wrap the command named `command’ in
table.

Replace command in the command table
with wrapper. The wrapped command will
be inserted into the command table
specified by the table argument. The
wrapper will be called like
wrapper(orig, *args, **kwargs) where
orig is the original (wrapped)
function, and *args, **kwargs are the
arguments passed to it.

A couple examples:

• The prompt extension by Steve Losh
• The nobranch extension from Fog Creek