Nothing, of course. I just find the macros that give you a "modified environment" to run some code short and sweet.

with-temp-buffer is another example: a macro that bridges the functions for "string manipulation" and the ones for "buffer manipulation", since you start writing stuff this way:

  (defun replace-in-string (str from to) 
    (with-temp-buffer
      (insert str)
      (beginning-of-file)
      ;;; Here you can use all your normal text editing commands
      (replace-regexp from to nil t)         
      (buffer-string)))

Lots of dirty manipulation, but from outside its a pure function, and doesn't change the editor state in any way after it runs.

That's incomplete in that it doesn't automatically chdir back. A proper block-scope "with-" macro will wrap the body in something like:

    char *olddir = getcwd();
    chdir(newdir);
    try {
        do_stuff();
    } finally {
        chdir(olddir);
    }

'try' and 'finally' are in C now? Someone should warn the GCC guys they're behind the times.

Also, getcwd has a size parameter these days, and of course you want to check if the getcwd actually worked.

The OP said: wrap in a macro having similar properties (ala pseudo code).

setjmp and longjmp are sufficient building blocks for this.

you can definitely save the chdir and restore it macro.

Any multithreaded code will be destroyed if relying on chdir. chdir should be deprecated, as resolving relative to is just trivial in an application.