nwsFetchTry               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:

     Attempt to fetch value associates with a variable from the shared
     netWorkSpace;  a non-blocking version of 'nwsFetch'.

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

     ## S4 method for signature 'netWorkSpace':
     nwsFetchTry(.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:

     Look in the shared netWorkSpace for a value bound to xName.  If
     found, remove a value associated with xName from the shared
     netWorkSpace. This operation is atomic. If there are multiple
     NetWorkSpaces clients nwsFetch or nwsFetchTry a given xName, any
     given value from the set of values associated with xName will be
     returned to just one client session. 

     If variable is not found, return immediately rather than block on
     the  operation (as in the case of 'nwsFetch'). If variable is not
     found, the value of argument  defaultVal is returned. By default,
     defaultVal is NULL.

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

     'nwsDeclare', 'nwsFetch'

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

     ## Not run: 
     ws <- netWorkSpace('nws example')
     # If variable 'x' is not found in the shared netWorkSpace,
     # return default value, NULL.
     nwsFetchTry(ws, 'x')
     # If variable 'x' is not found in the shared netWorkSpace, return 10.
     nwsFetchTry(ws, 'x', 10)
     ## End(Not run)

