formals                 package:base                 R Documentation

_A_c_c_e_s_s _t_o _a_n_d _M_a_n_i_p_u_l_a_t_i_o_n _o_f _t_h_e _F_o_r_m_a_l _A_r_g_u_m_e_n_t_s

_D_e_s_c_r_i_p_t_i_o_n:

     Get or set the formal arguments of a function.

_U_s_a_g_e:

     formals(fun = sys.function(sys.parent()))
     formals(fun) <- list

_A_r_g_u_m_e_n_t_s:

     fun: a function object or a character string naming the function
          to be manipulated. If not specified, the function calling
          `body' is used.

    list: a list of R expressions.

_V_a_l_u_e:

     `formals' returns the formal argument list of the function
     specified.

     The assignment form sets the formals of a function to the list on
     the right hand side.

_S_e_e _A_l_s_o:

     `args' for a ``human-readable'' version, `alist', `body',
     `function'.

_E_x_a_m_p_l_e_s:

     length(formals(lm))      # the number of formal arguments
     names(formals(boxplot))  # formal arguments names

     f <- function(x)a+b
     formals(f) <- alist(a=,b=3) # function(a,b=3)a+b
     f(2) # result = 5

