py-mod-subst.rst

ZConfig.substitution --- String substitution

.. automodule:: ZConfig.substitution

This module provides a basic substitution facility similar to that found in the Bourne shell (sh on most UNIX platforms).

The replacements supported by this module include:

Source	Replacement	Notes
$$	$
$name	The result of looking up name
${name}	The result of looking up name
$(name)	The result of looking up name in the environment

Notes:

1. This is different from the Bourne shell, which uses \$ to generate a $ in the result text. This difference avoids having as many special characters in the syntax.
2. Any character which immediately follows name may not be a valid character in a name.

In each case, name is a non-empty sequence of alphanumeric and underscore characters not starting with a digit. If there is not a replacement for name, the exception :exc:`~.SubstitutionReplacementError` is raised. Note that the lookup is expected to be case-insensitive; this module will always use a lower-case version of the name to perform the query.

This module provides these functions:

.. autofunction:: substitute

.. autofunction:: isname

Examples

>>> from ZConfig.substitution import substitute
>>> d = {'name': 'value',
...      'top': '$middle',
...      'middle' : 'bottom'}
>>>
>>> substitute('$name', d)
'value'
>>> substitute('$top', d)
'$middle'