tarListCallback         package:Rcompression         R Documentation

_C_a_l_l_b_a_c_k _f_u_n_c_t_i_o_n _t_o _g_a_t_h_e_r _i_n_f_o_r_m_a_t_i_o_n _a_b_o_u_t _e_n_t_r_i_e_s _i_n _a
_g_z_i_p_p_e_d _t_a_r _f_i_l_e.

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

     This is a function that returns two functions that can be used in
     a call to 'tarInfo' to collect the information about each entry in
     a gzipped tar archive. The first function  is called for each
     entry and combines the information for it with previously
     processed entries. The second function converts the data into a
     data frame, transforming time information into POSIXct values and
     mapping internal type identifiers for the entries into
     human-readable types, e.g. DIRTYPE, REGTYPE, ...

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

     tarListCallback()

_V_a_l_u_e:

     A list of two functions 

callback: the function that is to be invoked for each entry as it is
          encountered

    .ans: the function to retrieve the answer. This can be return the
          data as a simple list if it is called with the argument
          'FALSE'

     The list of functions is given a class TarInfoCallback to identify
     it as being a pair that 'tarInfo' can use together.

_A_u_t_h_o_r(_s):

     Duncan Temple Lang

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

     'tarInfo'

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

       filename = system.file("sampleData", "OmegahatXSL_0.2-0.tar.gz", package = "Rcompression")
       f = tarListCallback()
       invisible(tarInfo(filename, f$callback))
       f$.ans()

