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I'm asking here because i have already tried to search but i have no idea if this things even exist and what their names are.

I start explaining that with custom pattern i mean this: suppose that i need to serialize objects or data of type foo, bar and boo, usually the library handle this for the user in a very simple way, what comes first goes in first in the serialization process, so if i serialize all the foo first they are written "at the top" of the file and all the bar and boo are after the foo.

Now I would like to keep order in my file and organize things based on a custom pattern, it's this possible with Boost ? What section provides this feature ?

Second thing, that is strictly related to the first one, I also would like to access my serialized binary files in a way that I'm not forced to parse and read all the previous values to extract only the one that I'm interested in, kinda like the RAM that works based on memory address and offers a random access without forcing you to parse all the others addresses.

Thanks.

user1802174
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On the first issue: the Boost serialization library is agnostic as to what happens after it turns an object into its serialized form. It does this by using input and output streams. Files are just that - fostream/fistream. For other types of streams however, the order/pattern that you speak of doesn't make sense. Imagine you're sending serialized objects over the network - the library can't know that it'll have to rearrange the order of objects and, in fact, it can't do that once they've been sent. For this reason, it does not support what you're looking for.

What you can do is create a wrapper that either just caches serialized versions of the objects and arranges them in memory before you tell it to write them out to a file, or that knows that since you're working with files, it can later tellg to the appropriate place in the file and append (this approach would require you to store the locations of the objects you wrote to the file).

As for the second thing - random access file reading. You will have to know exactly where the object is in memory. If you know that the structure of your file won't change, you can seekg on the file stream before handing it to boost for deserialization. If the file structure will change however, you still need to know the location of objects in the file. If you don't want to parse the file to find it, you'll have to store it somewhere during serialization. For example - you can maintain a sort of registry of objects at the top of the file. You will still have to parse it, but it should be just a simple [Object identifier]-[location in file] sort of thing.

mtsvetkov
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  • no network involved here, i just want to be free to invoke the save and load function for the serialization anywhere in the code, without checking for previous de-serialization or without caching results. This effort is about keeping both my code clean and the business logic simple , if i could do this It would be the perfect solution for me and i can really use my serialized files effectively with a custom format. – user1802174 Nov 15 '12 at 16:50
  • I only mentioned the network thing as an example of why boost does not support what you're looking for. If you want to keep everything clean you could implement your own stream that would find the appropriate place in the file for each object (basically the idea from the second paragraph above, only built into the stream as opposed a separate cache). – mtsvetkov Nov 16 '12 at 12:02