New submission from Ben Kehoe <b...@kehoe.io>:
Currently, the only thing that can be done with a string.Template instance and
a mapping is either attempt to substitute with substitute() and catch a
KeyError if some identifier has not been provided in the mapping, or substitute
with safe_substitute() and not know whether all identifiers were provided.
I propose adding a method that returns the identifiers in the template. Because
the template string and pattern are exposed, this is already possible as a
separate function:
def get_identifiers(template):
return list(
set(
filter(
lambda v: v is not None,
(mo.group('named') or mo.group('braced')
for mo in template.pattern.finditer(template.template))
)
)
)
However, this function is not easy for a user of string.Template to construct
without learning how the template pattern works (which is documented but
intended to be learned only when subclassing or modifying id patterns).
As a method on string.Template, this would enable use cases like more
comprehensive error handling (e.g., finding all missing mapping keys at once)
or interactive prompting.
----------
components: Library (Lib)
messages: 410112
nosy: ben11kehoe
priority: normal
severity: normal
status: open
title: string.Template should allow inspection of identifiers
type: enhancement
versions: Python 3.11
_______________________________________
Python tracker <rep...@bugs.python.org>
<https://bugs.python.org/issue46307>
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