nwsIFetchTry               package:nws               R Documentation

_n_e_t_W_o_r_k_S_p_a_c_e _C_l_a_s_s _M_e_t_h_o_d

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

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

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

     ## S4 method for signature 'netWorkSpace':
     nwsIFetchTry(.Object, xName, defaultVal=NULL)

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

 .Object: a netWorkSpace class object

   xName: name of the variable to be fetched

defaultVal: value to return, if xName is not found in the netWorkSpace

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

     The iterator function returned by the nwsIFetchTry method takes no
     arguments, and works just like the nwsFetchTry method, specified
     with the same arguments that were passed to nwsIFetchTry method.
     Note that the nwsIFind and nwsIFindTry methods are much more
     useful, since they provide the only way to iterate over values of
     a variable non-destructively. nwsIFetch and nwsIFetchTry are
     provided for completeness.

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

     'nwsFetchTry', 'nwsIFetch'

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

     ## Not run: 
     ws <- netWorkSpace('nws example')
     nwsStore(ws, 'x', 10)
     it <- nwsIFetchTry(ws, 'x', NA)
     it()  # returns the value 10
     it()  # returns NA
     ## End(Not run)

