Mailman 3 backticks delenda est - Python-Dev

Dec. 1, 2003

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"Raymond Hettinger" wrote
Advisory from a micro-performance hawk:  Backticks are faster than
repr()
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from timeit import Timer
min(Timer('`x`', 'x=1').repeat(3))
1.4857213496706265
min(Timer('repr(x)', 'x=1').repeat(3))
1.7748914665012876
Presumably because the backtick version doesn't have to look up 
'repr', then call it.
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def f1(a):
...   repr(a)
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def f2(a):
...   `a`  
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import dis
dis.dis(f1)
  2           0 LOAD_GLOBAL              0 (repr)
              3 LOAD_FAST                0 (a)
              6 CALL_FUNCTION            1
              9 POP_TOP             
             10 LOAD_CONST               0 (None)
             13 RETURN_VALUE        
dis.dis(f2)
  2           0 LOAD_FAST                0 (a)
              3 UNARY_CONVERT       
              4 POP_TOP             
              5 LOAD_CONST               0 (None)
              8 RETURN_VALUE
This is presumably something that a future optimiser could "fix",
once we have the no-shadowing-builtins rule enforced.

I don't think this is a serious enough problem to merit leaving the 
backticks in the std lib. I find them annoying, and hard to read.
In general, the backticks are in debugging and error handling code, 
so the performance penalty should be negligible.

Anthony

backticks delenda est

Anthony Baxter

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