source/texk/web2c/luatexdir/luasocket/src/except.h

   1 #ifndef EXCEPT_H
   2 #define EXCEPT_H
   3 /*=========================================================================*\
   4 * Exception control
   5 * LuaSocket toolkit (but completely independent from other modules)
   6 *
   7 * This provides support for simple exceptions in Lua. During the
   8 * development of the HTTP/FTP/SMTP support, it became aparent that
   9 * error checking was taking a substantial amount of the coding. These
  10 * function greatly simplify the task of checking errors.
  11 *
  12 * The main idea is that functions should return nil as its first return
  13 * value when it finds an error, and return an error message (or value)
  14 * following nil. In case of success, as long as the first value is not nil,
  15 * the other values don't matter.
  16 *
  17 * The idea is to nest function calls with the "try" function. This function
  18 * checks the first value, and calls "error" on the second if the first is
  19 * nil. Otherwise, it returns all values it received.
  20 *
  21 * The protect function returns a new function that behaves exactly like the
  22 * function it receives, but the new function doesn't throw exceptions: it
  23 * returns nil followed by the error message instead.
  24 *
  25 * With these two function, it's easy to write functions that throw
  26 * exceptions on error, but that don't interrupt the user script.
  27 \*=========================================================================*/
  28
  29 #include "lua.h"
  30
  31 int except_open(lua_State *L);
  32
  33 #endif