Re: asciz_equal & asciz_length & strncmp

[Bruno H. <br...@cl...>]

Hi Sam,

> What's the status of these functions?

asciz_equal and asciz_length are the usual functions to use on C strings.

> Are they officially obsolete?

No.

> ISTR that strlen and strmp were avoided because they used registers that
> CLISP reserved for itself - it this still the case?

I avoided strlen and strcmp because
  * As you say, we cannot expect that libc functions respect our choices
    of reserved CPU registers. Thus the need to wrap calls of strlen and
    strcmp between begin_system_call() / end_system_call().
  * I also like the naming because "asciz" is just one data type among
    many others, and we have a function named asciz_to_string. In other
    words, the C and POSIX standards have terrible naming conventions.
    (Could you tell me, without looking it up, what is the difference
    between memcpy, mempcpy, and memccpy?)

> When can I use strncmp(3)? (we don't have a replacement)

strncmp is very easily used in the wrong way. (I guess I do it wrong
1 out of 2 times.) I prefer APIs that are maybe less general, but have
a semantics that is easier to grasp, such as
  boolean asciz_startswith (const char* s, const char* prefix)
or
  /* If s starts with the prefix, return the portion of s after the prefix,
     otherwise return NULL. */
  const char* asciz_tail (const char* s, const char* prefix)

Bruno