Re: [boost] [outcome] Ternary logic -- need an example

Subject: Re: [boost] [outcome] Ternary logic -- need an example
From: Peter Dimov (lists_at_[hidden])
Date: 2017-05-20 14:28:03

Vinnie Falco wrote:

> However, the [HTTP] status code is part of the message and therefore 
> should be part of the container. I do not think it should be treated as 
> metadata, nor represented using error_code.

Consider this high-level function

    result<vector<char>> get( string const& url );

used like this

    auto r = get( "https://example.com/data.zip" );

This function can fail in many different ways, starting from the URL parser 
(invalid URL), passing through the possibility of an invalid/unrecognized 
URL scheme, a host that cannot be resolved, a TCP address that can't be 
connected to, and finally, a 404 HTTP error code.

All these things should come back as std::error_code. There's no HTTP 
message here on this layer to contain the status.