Something needs to happen with shared, and soon.

[Michel Fortin]

On 2012-11-14 14:30:19 +0000, Timon Gehr <timon.gehr at gmx.ch> said:

> On 11/14/2012 01:42 PM, Michel Fortin wrote:
>> On 2012-11-14 10:30:46 +0000, Timon Gehr <timon.gehr at gmx.ch> said:
>> 
>>> So do I. A thread-local static variable does not imply global state.
>>> (The execution stack is static.) Eg. in a few cases it is sensible to
>>> use static variables as implicit arguments to avoid having to pass
>>> them around by copying them all over the execution stack.
>>> 
>>> private int x = 0;
>>> 
>>> int foo(){
>>>      int xold = x;
>>>      scope(exit) x = xold;
>>>      x = new_value;
>>>      bar(); // reads x
>>>      return baz(); // reads x
>>> }
>> 
>> I'd consider that poor style.
> 
> I'd consider this a poor statement to make. Universally quantified 
> assertions require more rigorous justification.

Indeed. There's not enough context to judge fairly. I can accept the 
idea there are situations where it is really inconvenient or impossible 
to pass the state as an argument.

That said, I disagree that this is not using global state. It might not 
be globally accessible (because x is private), but the state still 
exists globally since variable x exists in all threads irrespective of 
whether they use foo or not.


> If done in such a way that it makes refactoring error prone, it is to 
> be considered poor style.

I guess we agree.

-- 
Michel Fortin
michel.fortin at michelf.ca
http://michelf.ca/