Shouldn't this go to python-ideas? Anyway, I'm partial to "static".
~/santa On Sat, Mar 5, 2011 at 8:33 PM, Westley Martínez <aniko...@gmail.com> wrote: > On Sat, 2011-03-05 at 18:37 -0800, John Nagle wrote: > > On 3/2/2011 9:27 PM, Steven D'Aprano wrote: > > > On Wed, 02 Mar 2011 19:45:16 -0800, Yingjie Lan wrote: > > > > > >> Hi everyone, > > >> > > >> Variables in Python are resolved dynamically at runtime, which comes > at > > >> a performance cost. However, a lot of times we don't need that > feature. > > >> Variables can be determined at compile time, which should boost up > > >> speed. > > > [...] > > > > > > This is a very promising approach taken by a number of projects. > > > > It's worth having some syntax for constants. I'd suggest > > using "let": > > > > let PI = 3.1415926535897932384626433832795028841971693993751 > > > > I'd propose the following semantics: > > > > 1. "let" creates an object whose binding is unchangeable. This > > is effectively a constant, provided that the value is immutable. > > A compiler may treat such variables as constants for optimization > > purposes. > > > > 2. Assignment to a a variable created with "let" produces an error > > at compile time or run time. > > > > 3. Names bound with "let" have the same scope as any other name > > created in the same context. Function-local "let" variables > > are permitted. > > > > 4. It is an error to use "let" on a name explicitly made "global", > > because that would allow access to the variable before it was > > initialized. > > > > This is close to the semantics of "const" in C/C++, except that > > there's no notion of a const parameter. > > > > "let" allows the usual optimizations - constant folding, hoisting > > out of loops, compile time arithmetic, unboxing, etc. Ordinarily, > > Python compilers have to assume that any variable can be changed > > at any time from another thread, requiring worst-case code for > > everything. > > > > John Nagle > I'm against constants, for the purpose of "programmers should be smart > enough to not set a variable to another value that should be static", > but if Python were to have constants I think it would be better to use > something more descriptive than 'let'. Also, because the defined > constant is static, I think it would be better to use 'is' instead of > '='. Example: > > constant x is 5 > > -- > http://mail.python.org/mailman/listinfo/python-list >
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