nwsIFind                 package:nws                 R Documentation

_I_t_e_r_a_t_e _T_h_r_o_u_g_h _S_t_o_r_e_d _V_a_l_u_e_s _o_f _a _n_e_t_W_o_r_k_S_p_a_c_e _V_a_r_i_a_b_l_e

_D_e_s_c_r_i_p_t_i_o_n:

     Create a function that acts as a non-destructive iterator over the
     values of the specified variable.

_U_s_a_g_e:

     ## S4 method for signature 'netWorkSpace':
     nwsIFind(.Object, xName)

_A_r_g_u_m_e_n_t_s:

 .Object: a netWorkSpace class object.

   xName: character string specifying the name of the variable to be
          fetched.

_D_e_t_a_i_l_s:

     The iterator function returned by the 'nwsIFind' method takes no
     arguments, and works somewhat like the 'nwsFind' method, specified
     with the same arguments that were passed to 'nwsIFind'. The
     difference is that the 'nwsFind' method cannot iterate through the
     values of a variable; it always returns the same value until the
     variable is modified. The iterator function, however, maintains
     some state that allows it to see subsequent values. Each time the
     iterator function is called, it returns the next value in the
     variable. Once all values in the variable have been returned, the
     iterator function blocks, waiting for a new value to be stored in
     the variable.

_S_e_e _A_l_s_o:

     'nwsFind', 'nwsIFindTry'

_E_x_a_m_p_l_e_s:

     ## Not run: 
     ws <- netWorkSpace('nws example')
     nwsStore(ws, 'x', 1)
     nwsStore(ws, 'x', 2)
     it <- nwsIFind(ws, 'x')
     it()  # returns the value 1
     it()  # returns the value 2
     it()  # blocks until another process stores a value in the variable
     ## End(Not run)

