commit 8ba4523cccf59093543cec988b07957193d55692
parent 979ad95eb114d8d43f928b184f051ac0cfacedf7
Author: Roberto Ierusalimschy <roberto@inf.puc-rio.br>
Date: Wed, 10 Apr 2019 12:57:47 -0300
'print' does not call 'tostring' to format its arguments
Diffstat:
3 files changed, 16 insertions(+), 28 deletions(-)
diff --git a/lbaselib.c b/lbaselib.c
@@ -24,18 +24,12 @@
static int luaB_print (lua_State *L) {
int n = lua_gettop(L); /* number of arguments */
int i;
- lua_getglobal(L, "tostring");
- for (i=1; i<=n; i++) {
- const char *s;
+ for (i = 1; i <= n; i++) { /* for each argument */
size_t l;
- lua_pushvalue(L, -1); /* function to be called */
- lua_pushvalue(L, i); /* value to print */
- lua_call(L, 1, 1);
- s = lua_tolstring(L, -1, &l); /* get result */
- if (s == NULL)
- return luaL_error(L, "'tostring' must return a string to 'print'");
- if (i>1) lua_writestring("\t", 1);
- lua_writestring(s, l);
+ const char *s = luaL_tolstring(L, i, &l); /* convert it to string */
+ if (i > 1) /* not the first element? */
+ lua_writestring("\t", 1); /* add a tab before it */
+ lua_writestring(s, l); /* print it */
lua_pop(L, 1); /* pop result */
}
lua_writeline();
diff --git a/manual/manual.of b/manual/manual.of
@@ -6143,8 +6143,10 @@ In case of any error, @id{pcall} returns @false plus the error object.
@LibEntry{print (@Cdots)|
Receives any number of arguments
and prints their values to @id{stdout},
-using the @Lid{tostring} function to convert each argument to a string.
-@id{print} is not intended for formatted output,
+converting each argument to a string
+following the same rules of @Lid{tostring}.
+
+The function @id{print} is not intended for formatted output,
but only as a quick way to show a value,
for instance for debugging.
For complete control over the output,
@@ -8773,6 +8775,13 @@ like any other error when calling a finalizer.)
@itemize{
@item{
+The function @Lid{print} does not call @Lid{tostring}
+to format its arguments;
+instead, it has this functionality hardwired.
+You should use @id{__tostring} to modify how values are printed.
+}
+
+@item{
The pseudo-random number generator used by the function @Lid{math.random}
now starts with a somewhat random seed.
Moreover, it uses a different algorithm.
diff --git a/testes/calls.lua b/testes/calls.lua
@@ -21,21 +21,6 @@ assert(type(f) == 'function')
assert(not pcall(type))
-do -- test error in 'print' too...
- local tostring = _ENV.tostring
-
- _ENV.tostring = nil
- local st, msg = pcall(print, 1)
- assert(st == false and string.find(msg, "attempt to call a nil value"))
-
- _ENV.tostring = function () return {} end
- local st, msg = pcall(print, 1)
- assert(st == false and string.find(msg, "must return a string"))
-
- _ENV.tostring = tostring
-end
-
-
-- testing local-function recursion
fact = false
do
