--- title: Eboard 10 More Fun with Macros number: 10 section: eboards held: 2017-04-13 --- CSC 282.01, Class 10: More Fun with Macros =========================================== _Overview_ * Preliminaries * Notes and news * Upcoming work * Questions * Lab! ### News / Etc. * Sorry that the assignment come out too late. This one will be more timely. ### Upcoming work * Homework: Something involving `uthash.h` or `` ### Good things to do * 11am Faculty Governance Discussions * 11am-1pm Spark Tank presentations * CS Extras at 4:15 * James McBride at 4:15ish * Movie at 5 at Strand * Director talk at 6:30 pm JRC 101 free pizza * Some famous guy giving multimedia talk on Politics of Masculinity 7pm Harris * Music faculty performance 7:30 pm in Sebring-Lewis * Godspell is 7:30 pm at Loft (sold out) * James McBride and his band 8:00 pm in Herrick ### Questions Review * Macros are awesome - Text substitution is your friend * Common Lisp Macros are better than C macros * Scheme Macros may eventually be hygenic, which is even better * Great for logging/testing * Use assert * Write our own custom version of assert * Useful for writing DRY code Detour: `assert` ---------------- * It's a macro. * You can see how it is defined in `/usr/include/assert.h` * Note: Consider the following ``` assert (sqrt(4) == 2); ``` This normally gets expanded to some strange code like ``` if (! (sqrt(4) == 2)) { fprintf (stderr, ...); exit(0); }; ``` You can turn off assert with `-DNDEBUG`. If we just define `assert(X)` as nothing, we get ``` ; ``` Two approaches ``` #ifdef NDEBUG #define assert(X) (void (0)) #define assert(X) do { } while (0) #endif ``` Detour: Why do we use the `do ... while(0)` ------------------------------------------- * Some random Stackoverflow page at reminds me that we consume the semicolon for multi-statment macros because it's necessary for an `if` ``` if (test) MACRO(stuff); else other_stuff(); ``` Lab --- Clone Write a simple test program for stacks of `int` values.