[Python-Dev] Simple Switch statement
g.brandl at gmx.net
Mon Jun 26 01:12:30 CEST 2006
Raymond Hettinger wrote:
>>>No thanks. That is its own can of worms. The obvious solutions (like const
>>>declarations, macros, or a syntax to force compile-time expression
>>>are unlikely to sit well because they run afoul Python's deeply ingrained
>>I think perhaps you haven't been paying close attention to Fredrik's
> Yes, I have been. That is one of the three options I listed above.
> Each has its own issues.
> The static() keyword works like Forth's brackets for forcing
> compile-time evaluation. The issue for us is that unlike other Python
> expressions, there are inconvenient limitiations on what can be
> expressed inside:
> five = 5
> eight = 
> def f(x, six=6):
> seven = 7
> a = static(five + 4) # this is legal
> b = static(six + 4) # this is illegal
> c = static(seven + 4) # this is illegal
> d = static(eight + ) # this is illegal
Why would the last line be illegal?
> That will be a perpetual maintenance trap and conundrum for newbies.
In contrary to other "newbie traps" such as mutable default arguments, if
this would give a clear exception message like
"function-local name cannot be used in static expression", I can't imagine
it would be a bigger problem than e.g. "why is my floating point result
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