Re: [boost] Environment Variables Library?

Subject: Re: [boost] Environment Variables Library?
From: Gavin Lambert (gavinl_at_[hidden])
Date: 2015-05-21 19:20:32

On 21/05/2015 22:59, Michael Ainsworth wrote:
> Regarding the PATH variable (and other “array-like”
character-delimited environment variables), I was thinking of
implementing this with iterators. For example:
>
> namespace env = boost::environment;
> environment& current = env::current_environment();
>
> env::variable& path = current.get(“PATH”);
> for (env::variable::iterator it = path.begin(), end = path.end(); it  != end; ++it)
> {
>     std::cout << *it << std::endl;
> }
[...]
> path += "/var/lib/pgsql-9.4/bin";

I would recommend against this particular style.  Variables like PATH 
might be accessed either as a complete string (in which case += should 
do a normal string append without any separator, and the iterator would 
be the string's character iterator) or as individual components; it 
should be obvious which of these is being done.

If the goal is to have a cross-platform library, then I think that one 
of the following should be chosen:

1. A standalone library that only provides strings and makes no attempt 
to separate PATH into components.

2. A library that depends on Filesystem and provides both full-string 
access as well as a cross-platform way to split PATH (and other 
arbitrary variables) into Filesystem path components.

I don't think a half-measure (splitting paths but not using Filesystem) 
is desirable because it compromises the goal of being a portable 
library, since the path separators are different.