C - Exposing 3rd party data structures in a library's public header file

By -

I'm writing a library that wraps around a REST API and representing some of the data requires use of data structures like hash maps that are not available in the C standard library so internally I'm using 3rd party libraries for their implementations. Now I'd like to expose them in a response struct, I've come up with a couple of solutions:

  1. Just expose the type as it is and add a dependency on the 3rd party lib and make the user call the appropriate API functions (Eg hashmap_lib_get(users, "key") to get a value):
// header.h (Include guards excluded)
#include <hashmap_lib.h>

struct api_response {
    int field1;
    char *field2;
    HASHMAP_LIB_HM *users; // Map of users to their email. (example)
};

Issue: Requires extra user intervention, even more problematic in case the library is implemented using generic macros.

  1. Expose the type as a void pointer inside the struct and write duplicated wrappers for all appropriate functions:
// header.h
struct api_response {
    int field1;
    char *field2;
    void *users; // Don't touch
};

char *api_hashmap_get(void *hm, const char *key);

The internal implementation of api_hashmap_get would just be return hashmap_lib_get((HASHMAP_LIB_HM *) hm, key);

Issue: Requires duplication of various function definitions and requires the use of void pointers.

How is this problem usually solved in libraries ? The first solution would make sense if both the libraries were "related" with each other (Eg using an eventing system such as libevent to work with the user's application), but in this case it's just about general data structures so it doesn't make sense to me since the user would be using other libs for the same type of data structures aswell.



from Recent Questions - Stack Overflow https://ift.tt/3ouF1bJ
https://ift.tt/eA8V8J

Comments

Post a Comment

Popular posts from this blog

Today Walkin 14th-Sept

By -
Image
14th Sept 2017 ( GO Through all List) Read Walkin details properly , Try to call company before attending if possible !!! ==================================== 1. Myntra through fresherworld (Call Based , Venue shared to shortlisted candidates) _____________________________ 2. Magna : Hiring for Client Harman : C++
Read more

Spring Elasticsearch Operations

By -
Elasticsearch Operations Spring Data Elasticsearch uses two interfaces to define the operations that can be called against an Elasticsearch index. These are ElasticsearchOperations and ReactiveElasticsearchOperations. Whereas the first is used with the classic synchronous implementations, the second one uses reactive infrastructure. The default implementations of the interfaces offer: Read/Write mapping support for domain types. A rich query and criteria api. Resource management and Exception translation. ElasticsearchTemplate The ElasticsearchTemplate is an implementation of the ElasticsearchOperations interface using the Transport Client. @Configuration public class TransportClientConfig extends ElasticsearchConfigurationSupport {   @Bean   public Client elasticsearchClient() throws UnknownHostException {                      Settings settings = Settings.builder().put("cluster.name", "elasticsearch")....
Read more

Hibernate Search - Elasticsearch with JSON manipulation

By -
Elasticsearch with JSON manipulation Elasticsearch ships with many features. It is possible that at some point, one feature you need will not be exposed by the Search DSL. To work around such limitations, Hibernate Search provides ways to: Transform the HTTP request sent to Elasticsearch for search queries. Read the raw JSON of the HTTP response received from Elasticsearch for search queries. Direct changes to the HTTP request may conflict with Hibernate Search features and be supported differently by different versions of Elasticsearch. Similarly, the content of the HTTP response may change depending on the version of Elasticsearch, depending on which Hibernate Search features are used, and even depending on how Hibernate Search features are implemented. Thus, features relying on direct access to HTTP requests or responses cannot be guaranteed to continue to work when upgrading Hibernate Search, even for micro upgrades (x.y.z to x.y.(z+1)). Use this at your own risk....
Read more