constness of key in ngx_hash_find_
work at anomalizer.net
Mon Oct 20 16:26:24 MSD 2008
Igor Sysoev wrote:
> Do you mean
> -void *ngx_hash_find(ngx_hash_t *hash, ..., u_char *name,
> +void *ngx_hash_find(const ngx_hash_t *hash, ..., const u_char *name,
> But what will this improve ?
This is more of an API design/style question. When passing pointers, if
the function signature declares the argument to be "const type *ptr", it
tells me that the function will not modify the contents of the variable
being passed. For eg: A hash lookup function should never need to modify
either the hash or the key being searched for.
If a function violates this contract, then it results in a compile time
error. If someone tries to forcibly discard the constness using a
typecast, it will result in a warning.
Having the const declarations thus gives people the assurance that the
values being passed will not be modified inside the function. Without
that, I am not sure if the value will get modified unless I read the
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