Cheryl Sabella <chek...@gmail.com> added the comment:
For msg312444 on StringTranslatePseudoMapping:
I ran a comparison of the current class vs defaultdict.
This was my test:
```
with open('/home/cheryl/cpython/Lib/idlelib/pyparse.py') as fd:
code = fd.read()
copies = 20000
code *= copies
for i in range(10):
start = time.time()
trans_code = code.translate(_tran)
end = time.time()
print(f'copies: {copies} translate time: {end - start}')
```
I ran the current `_tran` first and saved the results.
```
_tran = {}
_tran.update((ord(c), ord('(')) for c in "({[")
_tran.update((ord(c), ord(')')) for c in ")}]")
_tran.update((ord(c), ord(c)) for c in "\"'\\\n#")
_tran = StringTranslatePseudoMapping(_tran, default_value=ord('x'))
```
I know time.time isn't perfect, but thought it might be good enough. The
results:
copies: 20000 translate time: 0.8162932395935059
copies: 20000 translate time: 0.610985517501831
copies: 20000 translate time: 0.8164870738983154
copies: 20000 translate time: 0.6125986576080322
copies: 20000 translate time: 0.8143167495727539
copies: 20000 translate time: 0.612929105758667
copies: 20000 translate time: 0.8299245834350586
copies: 20000 translate time: 0.6127865314483643
copies: 20000 translate time: 0.812185525894165
copies: 20000 translate time: 0.6151354312896729
Then I changed it to a defaultdict:
```
_tran = defaultdict(lambda: 'x')
# _tran = {}
_tran.update((ord(c), ord('(')) for c in "({[")
_tran.update((ord(c), ord(')')) for c in ")}]")
_tran.update((ord(c), ord(c)) for c in "\"'\\\n#")
# _tran = StringTranslatePseudoMapping(_tran, default_value=ord('x'))
```
I compared the results to make sure the defaultdict produced the same output as
the mapping, which it did.
The results:
copies: 20000 translate time: 0.8172969818115234
copies: 20000 translate time: 0.6214878559112549
copies: 20000 translate time: 0.8143007755279541
copies: 20000 translate time: 0.6127951145172119
copies: 20000 translate time: 0.8154017925262451
copies: 20000 translate time: 0.6144123077392578
copies: 20000 translate time: 0.8128812313079834
copies: 20000 translate time: 0.6167266368865967
copies: 20000 translate time: 0.8143749237060547
copies: 20000 translate time: 0.6116495132446289
So, the results are simliar, down to the alternating of .61ish and .81ish times.
----------
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Python tracker <rep...@bugs.python.org>
<https://bugs.python.org/issue32880>
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