Multiple patches

If you have more than one patch to apply:

>>> write(sample_buildout, 'another.patch',
... """diff --git demo.py demo.py
... --- demo.py
... +++ demo.py
... @@ -1,2 +1 @@
... -# demo egg
...  # patching
... """)

Update your buildout.cfg to list the new patch. In this case, another.patch should be applied after demo.patch:

>>> write(sample_buildout, 'buildout.cfg',
... """
... [buildout]
... parts = demo-patch
... index = demo/dist/
...
... [demo-patch]
... recipe = cykooz.recipe.patch
... egg = demo==1.0
... patches =
...     demo.patch
...     another.patch
... """)

Running the buildout gives us:

>>> rmdir(sample_buildout, 'develop-eggs', demoegg)
>>> remove(sample_buildout, '.installed.cfg')
>>> _ = system(buildout + ' setup demo bdist_egg')
>>> print_(system(buildout))
Installing demo-patch.
Getting distribution for 'demo==1.0'.
Got demo 1.0.
patch: reading patch .../demo.patch
...
patch: patching file demo.py
patch: successfully patched .../demo-1.0...
patch: reading patch .../another.patch
...
patch: patching file demo.py
patch: successfully patched .../demo-1.0...
...

>>> cat(sample_buildout, 'develop-eggs', demoegg, 'demo.py')
# patching

Patching an egg installed in another part

Another possibility is to install an egg with zc.recipe.egg (or probably any other recipe) and patch it afterwards. However, it is necessary to install the egg unzipped, and the egg may end up in the eggs-folder instead the develop-eggs folder.

>>> write(sample_buildout, 'buildout.cfg',
... """
... [buildout]
... parts = demo-egg demo-patch
... index = demo/dist/
...
... [demo-egg]
... recipe = zc.recipe.egg
... eggs = demo==1.0
...
... [demo-patch]
... recipe = cykooz.recipe.patch
... egg = ${demo-egg:eggs}
... patches = demo.patch
... """)

Running the buildout gives us:

>>> rmdir(sample_buildout, 'develop-eggs', demoegg)
>>> remove(sample_buildout, '.installed.cfg')
>>> _ = system(buildout + ' setup demo bdist_egg')
>>> print_(system(buildout))
Installing demo-egg.
Getting distribution for 'demo==1.0'.
Got demo 1.0.
Installing demo-patch.
patch: reading patch .../demo.patch
...
patch: patching file demo.py
patch: successfully patched .../demo-1.0...

>>> ls(sample_buildout, 'eggs', demoegg)
d  EGG-INFO
-  demo.py
-  demo.pyc
-  demo.pyo
>>> cat(sample_buildout, 'demo', 'demo.py')
# demo egg
>>> cat(sample_buildout, 'eggs', demoegg, 'demo.py')
# demo egg
# patching

Broken patches

If one of the patches is broken:

>>> write(sample_buildout, 'missing-file.patch',
... """diff --git missing-file.py missing-file.py
... --- missing-file.py
... +++ missing-file.py
... @@ -1,2 +0 @@
... -# BROKEN
... -# PATCH
... """)

When you try to apply multiple patches, it will fail to apply any subsequent patches, letting you fix the problem:

>>> write(sample_buildout, 'buildout.cfg',
... """
... [buildout]
... parts = demo-patch
... index = demo/dist/
...
... [demo-patch]
... recipe = cykooz.recipe.patch
... egg = demo==1.0
... patches = missing-file.patch
...           demo.patch
... """)

Running the buildout gives us:

>>> rmdir(sample_buildout, 'eggs', demoegg)
>>> remove(sample_buildout, '.installed.cfg')
>>> _ = system(buildout + ' setup demo bdist_egg')
>>> print_(system(buildout))
Installing demo-patch.
Getting distribution for 'demo==1.0'.
Got demo 1.0.
patch: reading patch .../missing-file.patch
...
patch: The next patch would delete the file missing-file.py,
patch: which does not exist!  Skipping patch.
patch: patch: **** malformed patch at line 6:
...
While:
  Installing demo-patch.
Error: could not apply .../missing-file.patch

>>> cat(sample_buildout, 'develop-eggs', demoegg, 'demo.py')
# demo egg