[EMAIL PROTECTED] on 05/03/2000 12:44:09 AM
>>I was looking at that, too. I tend to feel that 0-byte allocations should be
>>allowed (returning NULL) and, if systems' frees don't handle NULL properly,
>>there should be an xfree() that'll do so.
>
>I can see the occasional need to allocate a unique pointer that points to
>nowhere but is distinguishable from any other pointer, even NULL. Having a
>malloc-like function that does this (allocate a block of memory at least 0
>bytes long and return a pointer to it) is useful, and if it's implemented as
>a wrapper that increments a 0 size then so be it.
>
>This practice is typically used when there's a distinction to be made
>between an "unset" value and a "set but unspecified" value. An example
>of such data in CVS are commit comments: Comments can be prompted for if
>the string is unset. Or, an empty comment can be stored (without a prompt)
>if the string is set but unspecified.
>
>This is a somewhat contrived example because for strings this distinction
>is made by using a NULL pointer for an unset value, and a pointer to an
>empty string for a set but unspecified value. But for structures the
>distinction is a little harder to implement, and special pointers are
>one economical way to do it. Timestamps are another type of data where
>this distinction might be important, in many applications.
I don't understand why anyone would ever request a zero-byte allocation for a
struct nor how they'd be able to tell it apart from a "good" allocation. IMHO,
the way to perform the above would be to have an "isValid" field within the
struct.
Noel
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