assert
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assert package:gtools R Documentation
_G_e_n_e_r_a_t_e _a_n _e_r_r_o_r _i_f _a_n _e_x_p_r_e_s_s_i_o_n _i_s _n_o_t _t_r_u_e.
_D_e_s_c_r_i_p_t_i_o_n:
Generate an error if an expression is not true.
_U_s_a_g_e:
assert(FLAG)
_A_r_g_u_m_e_n_t_s:
FLAG: Expression that should evaluate to a boolean vector
_D_e_t_a_i_l_s:
Assert generate an error if its aregument does not evaluate to
boolean (vector) containing only 'TRUE' values. This is useful
for defensinve programming as it provides a mechanism for checking
that certain facts, the 'assertions', do in fact hold. Checking
of 'assertions' is an important tool in the development of robust
program code.
_V_a_l_u_e:
None. Evaluated only for its side effect.
_A_u_t_h_o_r(_s):
Gregory R. Warnes warnes@bst.rochester.edu
_S_e_e _A_l_s_o:
'stop', 'warning'
_E_x_a_m_p_l_e_s:
## Trivial example
posSqrt <- function(x)
{
assert(x>=0)
sqrt(x)
}
posSqrt(1:10) # works fine, no messages
## Not run:
posSqrt(-5:5) # generates an error, since the asssertion is not met
## End(Not run)