mercurial - Hg: extension search path -

i want use special extension, reasons want avoid modify mercurial installation , touch existing mercurial.ini or .hg/hgrc files. usually, invoke command like

hg --config extensions.hgext.foo=c:\path\to\my\extension.py ... 

if write just

hg --config extensions.hgext.foo=extension.py ... 

where mercurial search extension.py? there way configure environment variable can add/set c:\path\to\my path, mercurial find extensions.py without specifying full path?

assuming using windows cmd line interface, wrap entire config line cmd window's local environment var:

set enablefoo=--config extensions.hgext.foo=c:\path\to\my\extension.py 

then turn on given command by:

hg %enablefoo% foo -r tip 

note using local environment variable inline substituion before hg called; hg not affected or altered @ , isn't "searching" anything.