GeezerVison is showing github.com — gh-118761: Optimise import time for ``string`` by AA-Turner · Pull Request #132037 · python/cpython
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AA-Turner
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Apr 3, 2025
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edited by bedevere-app
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This PR achieves a 27x improvement in import time for the string module. The main improvement comes from replacing Template.__init_subclass__() (GH-16256) with a descriptor class, allowing lazy import of the re module.
Current:
import string: cumulative time
mean: 9162.100 µs
median: 9133.000 µs
stdev: 66.662
min: 9071
max: 9301
This PR:
import string: cumulative time
mean: 334.967 µs
median: 329.000 µs
stdev: 13.438
min: 316
max: 368
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I'm very happy with this because I need to access many times string.* constants without needing the Template class so it's a very good optimization.
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Interesting idea. The code looks intimidating, but it might work.
How the help output looks now?
Is __init_subclass__() needed anymore?
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Help output looks fine:
>>> from string import Template
>>> assert Template.flags is None
>>> help(Template)
Help on class Template in module string:
class Template(builtins.object)
| Template(template)
|
| A string class for supporting $-substitutions.
|
| Methods defined here:
|
| __init__(self, template)
| Initialize self. See help(type(self)) for accurate signature.
|
| get_identifiers(self)
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| is_valid(self)
|
| safe_substitute(self, mapping={}, /, **kws)
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| substitute(self, mapping={}, /, **kws)
|
| ----------------------------------------------------------------------
| Class methods defined here:
|
| __init_subclass__()
| This method is called when a class is subclassed.
|
| The default implementation does nothing. It may be
| overridden to extend subclasses.
|
| ----------------------------------------------------------------------
| Data descriptors defined here:
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| __dict__
| dictionary for instance variables
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| __weakref__
| list of weak references to the object
|
| ----------------------------------------------------------------------
| Data and other attributes defined here:
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| braceidpattern = None
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| delimiter = '$'
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| flags = re.IGNORECASE
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| idpattern = '(?a:[_a-z][_a-z0-9]*)'
|
| pattern = re.compile('\n \\$(?:\n ...identifie...
>>>
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It perhaps could be made simpler with classmethod + property, but the future of this feature is not clear.
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picnixz
Awaiting requested review from picnixz
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