source: products/quintagroup.transmogrifier/trunk/quintagroup/transmogrifier/substitution.txt @ 1589

Substitution section
====================

A substitution pipeline section lets you substitute item's value stored
on some key with value given in options. The substitution section blueprint
name is ``quintagroup.transmogrifier.substitution``.

Substition is performed in this way: if section has option with name that
is equal to value stored on this key, than value of this option is used
as new value for this key. Old value is stored on ``_old${key}`` key.
Which key to use is determined by ``key`` option.

>>> substitution = """
... [transmogrifier]
... pipeline =
...     source
...     substitution
...     printer
... 
... [source]
... blueprint = quintagroup.transmogrifier.tests.substitutionsource
... 
... [substitution]
... blueprint = quintagroup.transmogrifier.substitution
... key = _type
... Blog = Weblog
... PloneFormMailer = FormFolder
... 
... [printer]
... blueprint = collective.transmogrifier.sections.tests.pprinter
... """
>>> registerConfig(u'quintagroup.transmogrifier.tests.substitution', substitution)
>>> transmogrifier(u'quintagroup.transmogrifier.tests.substitution') # doctest: +ELLIPSIS, +REPORT_NDIFF
{}
{'_old_type': 'Blog', '_type': 'Weblog'}
{'_old_type': 'PloneFormMailer', '_type': 'FormFolder'}
{'_type': 'Document'}