Substitute Values of Variables in Functions That Hold Their Arguments
Define a held expression that refers to the variable x:
In[1]:=1

✖

Because Hold has the attribute HoldAll, x is not evaluated when the held expression is defined, so the body of the expression refers to the global variable x. The value of x is obtained when the Hold is released:
In[2]:=2

✖
Out[2]=2

To effectively force x to evaluate when the held expression is defined, use With:


Now changes in the value of x have no effect on the value returned when the Hold is released:
In[4]:=4

✖
Out[4]=4
