view tests/test-template-engine.t @ 38162:bdf344aea0ee

extensions: peek command table of disabled extensions without importing

With chg where demandimport disabled, and if disk cache not warm, it took
more than 5 seconds to get "unknown command" error when you typo a command
name. This is horrible UX.

The new implementation is less accurate than the original one as Python
can do anything at import time and cmdtable may be imported from another
module, but I think it's good enough.

Note that the new implementation has to parse .py files, which is slightly
slower than executing .pyc if demandimport is enabled.

  $ cat > engine.py << EOF
  > 
  > from mercurial import (
  >     pycompat,
  >     templater,
  >     templateutil,
  > )
  > 
  > class mytemplater(templater.engine):
  >     def _load(self, t):
  >         return self._loader(t)
  > 
  >     def process(self, t, map):
  >         tmpl = self._load(t)
  >         props = self._defaults.copy()
  >         props.update(map)
  >         for k, v in props.items():
  >             if b'{{%s}}' % k not in tmpl:
  >                 continue
  >             if callable(v) and getattr(v, '_requires', None) is None:
  >                 props = self._resources.copy()
  >                 props.update(map)
  >                 v = v(**pycompat.strkwargs(props))
  >             elif callable(v):
  >                 v = v(self, props)
  >             v = templateutil.stringify(self, props, v)
  >             tmpl = tmpl.replace(b'{{%s}}' % k, v)
  >         yield tmpl
  > 
  > templater.engines[b'my'] = mytemplater
  > EOF
  $ hg init test
  $ echo '[extensions]' > test/.hg/hgrc
  $ echo "engine = `pwd`/engine.py" >> test/.hg/hgrc
  $ cd test
  $ cat > mymap << EOF
  > changeset = my:changeset.txt
  > EOF
  $ cat > changeset.txt << EOF
  > {{rev}} {{node}} {{author}}
  > EOF
  $ hg ci -Ama
  adding changeset.txt
  adding mymap
  $ hg log --style=./mymap
  0 97e5f848f0936960273bbf75be6388cd0350a32b test

  $ cat > changeset.txt << EOF
  > {{p1rev}} {{p1node}} {{p2rev}} {{p2node}}
  > EOF
  $ hg ci -Ama
  $ hg log --style=./mymap
  0 97e5f848f0936960273bbf75be6388cd0350a32b -1 0000000000000000000000000000000000000000
  -1 0000000000000000000000000000000000000000 -1 0000000000000000000000000000000000000000

invalid engine type:

  $ echo 'changeset = unknown:changeset.txt' > unknownenginemap
  $ hg log --style=./unknownenginemap
  abort: invalid template engine: unknown
  [255]

  $ cd ..