Is PureMalloc actually... pure?
ckatko at gmail.com
Sat Jan 11 19:05:48 UTC 2020
Pure implies (*requires) no side effects, right?
>UNIX 98 requires that errno be set to ENOMEM upon failure.
>Purity is achieved by saving and restoring the value of errno,
>thus behaving as if it were never changed.
Saving and restoring a global variable is is __not__ the same as
no side effects. without a mutex, two threads could easily create
a date race.
void* pureMalloc()(size_t size) @trusted pure @nogc nothrow
const errnosave = fakePureErrno;
void* ret = fakePureMalloc(size);
fakePureErrno = errnosave;
I mean, on a practical level, malloc almost never fails so this
probably hasn't shown up as a bug in 99% of code.
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