[Python-Dev] backticks delenda est

[Anthony Baxter]

>>> "Raymond Hettinger" wrote
> Advisory from a micro-performance hawk:  Backticks are faster than
> repr()
> 
> >>> 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. 

>>> def f1(a):
...   repr(a)
... 
>>> 
>>> def f2(a):
...   `a`  
... 
>>> 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