this post was submitted on 21 Jul 2024
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Cleanest way to manage unique objects in C++? (self.learn_programming)
submitted 5 months ago by drem to c/[email protected]
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Hello, I would like to store these http headers in classes:

Host: developer.mozilla.org
User-Agent: Mozilla/5.0 (Macintosh; Intel Mac OS X 10.9; rv:50.0) Gecko/20100101 Firefox/50.0
Accept: text/html,application/xhtml+xml,application/xml;q=0.9,*/*;q=0.8
Accept-Language: en-US,en;q=0.5
Accept-Encoding: gzip, deflate, br
Referer: https://developer.mozilla.org/testpage.html
Connection: keep-alive
Upgrade-Insecure-Requests: 1
If-Modified-Since: Mon, 18 Jul 2016 02:36:04 GMT
If-None-Match: "c561c68d0ba92bbeb8b0fff2a9199f722e3a621a"
Cache-Control: max-age=0

As you can see, many have unique data (numbers, strings, list of strings). I would like to:

  • store a header name
  • store list of possible options for that header (or store if it's a number)
  • read an input header and store and return the found option / list of options / number
  • make adding new types of headers as easy as possible

Is making hard coded classes for every type of header viable? How would this be done in the cleanest way possible?

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[–] pennomi 5 points 5 months ago* (last edited 5 months ago) (1 children)

The majority of HTTP frameworks I’ve used store headers in a dictionary, because the common denominator between all headers is that they are string keys and string values.

To clarify: you might think that some headers are lists of strings, but that’s not actually true - the user can send any string to you. You really open yourself up to parsing problems if somebody transmits a header in a format that cannot be represented by your data structure.

Oftentimes what a framework will do is store the headers in the dictionary, and then provide getters and setters to access “friendly” parsed versions of commonly used data (but only if it parses correctly).

[–] drem 1 points 5 months ago* (last edited 5 months ago) (1 children)

to access “friendly” parsed versions of commonly used data

What do you mean by this? And where is the header processing done? And btw thanks for your answer, I knew I was doing something wrong.

Edit: Are the possible options for headers stored in for example a header class, or are they just checked when clients are processed?

[–] pennomi 2 points 5 months ago

So for example in “requests”, a popular http framework in Python, there’s a class for the Response object. On that object you can access the special header dictionary at response.headers. Check the docs here under the section Response Headers

Basically they make a special dictionary that allows headers to be case-insensitive, and combining headers that are provided twice.

But they also provide a special property response.encoding which derives from the Content-Type header, just for convenience.

Hopefully that all makes sense.