Re: [boost] [url] Andrzej's notes

śr., 24 sie 2022 o 01:37 Vinnie Falco via Boost napisał(a):

On Tue, Aug 23, 2022 at 4:23 PM Gavin Lambert via Boost wrote:

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url_base& url_base::set_port( string_view ); // throws result<void> url_base::try_set_port( string_view ); // returns

result

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Why is it a string at all? Shouldn't it be exclusively a uint16_t?

Its a good question. Every member function in the reference has a BNF section which shows the grammar, and a Specification section which provides a link to the relevant specifications document (RFC3986 in this case):

< https://master.url.cpp.al/url/ref/boost__urls__url_base/set_port/overload2.h...

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The RFC says:

port = *DIGIT

That means that "80", "443", and "8080" are examples of valid ports. "65535" is a valid port. But so is "4294967295" or even "999999999999999999". In fact "0" is a valid port, as well as "00" or any number of leading zeroes, followed by any number of digits (including no digits). And the empty string "" is a valid port. Boost.URL recognizes the distinction between having a port which is the empty string, and not having a port at all, by providing the function remove_port() and the function has_port(). Calling set_port("") is semantically different from calling remove_port(), and results in a different URL. This is per the RFC grammar:

authority = [ userinfo "@" ] host [ ":" port ]

Because this library is capable of representing ALL URLs, it is necessary for the interface to allow the caller to interact with the port as a string which is valid according to the grammar.

Is this the only reason? I would think that the primary reason is performance: usually you obtain a URL as a string, so the port-string is just sitting there. Then you may want to set it in another URL, so it will be a string again. But of

course people need to treat it like an integer so we have overloads for setting the port as a sixteen bit unsigned number, and retrieving the port as the same.

https://master.url.cpp.al/url/ref/boost__urls__url/port_number.html < https://master.url.cpp.al/url/ref/boost__urls__url/set_port/overload1.html

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Oh, it wasn't clear from the docs. So, it looks like you are saying "I know it's an integer port number, you know it's an integer port number, but I need to keep it as string because other schemes may use it for their own murky schemes, like: "ak://www.boost.org" -- identifies one resource "ak://www.boost.org:" -- identifies another resource This convinces me even further that I might want a type like http_url with a tighter invariant: 1. The port is an optional int 2. The query part doesn't have duplicate keys. Regards, &rzej;