yade-dev team mailing list archive

[Vincent Richefeu <richefeu@xxxxxxxxxxxxxxx>]

Hi Vaclac,

Have you think about vector<bool> for this purpose?
As you certainly know it's a specialized template that hold bits (instead of bools).
In fact, I have not seen the code, but in the c++ point of view, something like :

  std::vector<bool> blockedDOFs; 
  blockedDOFs.reserve(3); // Actually, I don't remember... but something like that
  blockedDOFs[0] = true; 
  blockedDOFs[1] = false;
  blockedDOFs[2] = true;

will take the same place in memory and should maybe be easy to use.

Vincent



Le 28 janv. 2010 à 08:38, Václav Šmilauer a écrit :

>> However, it seems that, doing so, I can only manage 1 DOF as
>> blockedDOFs is a bitmask which can be chosen between these values:
> Well, read http://en.wikipedia.org/wiki/Bitmask and
> http://en.wikipedia.org/wiki/Bitwise_operation. Precisely because it is
> a bitmask, you have to set bits that correspond to RX, RY, RZ if you
> need to block just those, i.e. (8 & 16 & 32), which is binary 0b111000
> (in python) and that is decimal 56.
> 
> In yade moreover, try writing State.blockedDOFs? and enter, which will
> give you 
> https://www.yade-dem.org/sphinx/yade.wrapper.html#yade.wrapper.State.blockedDOFs
> and that reveals a simpler way that I put back then just for people that
> don't want to know what bitmask is, and that lest you say
> 
> state.blockedDOFs=['rx','ry','rz]
> 
> as well, which is the same as
> 
> state.blockedDOFs=56
> 
> which is the same as
> 
> state.blockedDOFs=(8 & 16 & 32)
> 
> which is the same as
> 
> state.blockedDOFs=0b111000
> 
> Prefer the 'rx','ry','rz' way, though, since those numbers are
> implementation detail and would break your code if that changed. It
> makes also the code more readable, obviously.
> 
> Cheers, Vaclav
> 
> 
> 
> 
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