View source for Talk:Parse an IP Address

Hm. I'm thinking the decimal number requirement isn't necessary. Removing. --[[User:Short Circuit|Michael Mol]] 12:35, 27 September 2011 (UTC)

== Sloppy ==

This task currently seems sloppy.

First, it requires that extra data (the port) be ignored.  In practical use, if the port is being passed to a routine that parses ip addresses, this probably means the data is being mishandled.  So good practice suggests that this be treated as an error case.  This is a minor but annoying complexity in the task.

Second, it asks us to mix ipv4 and ipv6 addresses but ipv4 addresses have a representation as ipv6 addresses (see rfc 2373, for example) but the example implementation mixes them in the same data structure without labeling the type and without using a consistent mapping.

I can think of several ways to go here:

# Discard the port parsing requirement
# Ask for ip,port to be reported as a pair
# Ask for ipv4 and ipv6 address results to be distinguished (or put them in separate tasks)
# Ask for the ipv4 addresses to be encoded as ipv6 addresses (127.0.0.1 becomes ::127.0.0.1 to distinguish it from ::7f00:1).
# change the task to make some of these issues moot

But I am not sure which way to go here. --[[User:Rdm|Rdm]] 13:58, 28 September 2011 (UTC)
: The trouble is, connection targets (IP/port combinations) are frequently passed around in ''string'' format with the version undeclared. Many programs which need to operate with IPv4 and IPv6 addresses actually have difficulty with it, even though the standardized formats are documented. Correctly converting that string representation into a logical representation is what this task is intended to be about. The inclusion of both IPv4 and IPv6 notation, as well as the inclusion ":portNumber", is intentional, to attempt reflect the full complexity of the problem. So what remains is likely a poorly chosen task title and an an insufficiently-described task. I have extreme difficulty being clear on the latter point, though. --[[User:Short Circuit|Michael Mol]] 14:27, 28 September 2011 (UTC)

:: The string format is unambiguous.  But result format is ambiguous, here.  --[[User:Rdm|Rdm]]
::: Ah, I see now. I only saw the output format of the task to be relevant in that it required comprehension of the input format to generate. The internal representation (in particular, correct distinction of host and port addresses) was what I was more interested in. Requiring the port address in the output helps a reviewer understand how the port number was understood. Change the requirements for the output format however you see fit, with that requirement in mind. (I'd try changing it, but I've been without my glasses for a week, and doing things on the computer has been very, very error-prone--even trying to write coherently. )--[[User:Short Circuit|Michael Mol]] 15:15, 28 September 2011 (UTC)

The 'bit specifying if port was given' doesn't seem necessary, how about just use port 0? --[[User:Ledrug|Ledrug]] 15:37, 28 September 2011 (UTC)
: Specifying port 0 means "any available", but only in some contexts. A more general solution should be preferred, IMO. I took the "bit specifying" bit as "an indicator", rather than as an explicit like-formatted boolean bit. The way I read it, it could be equally (and possibly more clearly) written as "a note specifying if port was given". --[[User:Short Circuit|Michael Mol]] 15:40, 28 September 2011 (UTC)

:I have (after several not-so-good attempts) done my best making the result format unambiguous and complete for this task.  Let me know what you think.
:Meanwhile, as Michael Mol points out, port 0 can be different from no port specified.  --[[User:Rdm|Rdm]] 15:47, 28 September 2011 (UTC)
:: The only part I don't understand is "In languages where variant result types are clumsy". --[[User:Short Circuit|Michael Mol]] 15:48, 28 September 2011 (UTC)
::: How would you represent the required results in C, for example?  --[[User:Rdm|Rdm]] 15:49, 28 September 2011 (UTC)