@Override
	public void setType(BlocType b) {
		BlocType t = super.getType();
		checkInvariants();
		super.setType(b);
		checkInvariants();
		if(t==BlocType.MURMETAL){
			if(!(super.getType() == BlocType.MURMETAL)){
				throw new PostConditionError(
						"getType(B) == BlocType::MURMETAL et "+
								"getType(setType(B,t)) != BlocType :: MURMETAL");}
		} else {
			if(!(super.getType()==b))
				throw new PostConditionError("getType(setType(B,t)) == t");
		}
			
		
	}