Re: Globals

Victor Bazarov <v.bazarov@comcast.invalid>
Fri, 05 Nov 2010 16:19:32 -0400
On 11/5/2010 3:59 PM, Andrea Crotti wrote:

Victor Bazarov<v.bazarov@comcast.invalid> writes:

You're assigning to it, aren't you? And you want the assignment to
stick, don't you? So, returning a temporary is OK if you don't care
that the value you assign isn't stored in the map itself and basically
immediately forgotten after the temporary goes away.

Uhm well I tried with the following
     string& operator[](const string& key) { return conf[key]; }
     string operator[](string& key) { return conf[key]; }
     string operator[](const string& key) { return conf[key]; }

and in all the three cases it works in the same way, if I assign
something I also find it after...

You do? Weird. I would expect that the two latter cases wouldn't work...

Yes, or you could simply have a static dummy object that would
initialize your map, like so:

     int dummy = GLOBALS_initializer_function(); // namespace scope

And fill up your GLOBALS map in that function... Of course, there is
always the static object initialization fiasco you need to worry
about. Make sure no static objects ever use your GLOBALS before it's
constructed (in case you go with the class) or filled in (if you go
with the initialization function).


Interesting the fiasco, but well a static object will always call a
constructor before going further?

Not sure what you mean by 'going further'? Read the FAQ.

Or should I just have another function "initialize()" and make sure it's
called before I start to read?

I am not convinced that it's going to help. Read the FAQ.

extern Globals CONF;

class Globals
Globals::Globals() {...}

and in Globals.cpp there is

Globals CONF;

Would that be already enough to avoid the fiasco?

May not be. Read the FAQ.

Or as they say on the FAQ should I create a function which creates this
global object (not so important if I can't clear it)??

Well, since you already read the FAQ, follow its suggestions.

And now instead another problem, supposing I have the following

You better start another thread.

--8<---------------cut here---------------start------------->8---
int x;
long y;
str::vector<string> z;
--8<---------------cut here---------------end--------------->8---

the idea was to use a mapping to avoid repetition in the assignment from
the ini file, so that I can just do

CONFIG["x"] = 100;
And use a for loop on the map.

Huh? Are you assuming I know the details of what you're trying to do
just as well as you do?

BUT I only read strings in the ini file, and I have to convert the
values somehow.

Converting strings is a very common problem, and there are tons of
available solutions, even in public domain, I am sure.

So the best thing would be to have a something like

{ x : (value, function),
   y : (value, function)

To have it WHERE? Are you aware we're not mind readers?

and then call the corresponding function.
Or what other data structure would be good?

I dunno.

How can I do that? Maybe a function pointer, like:

{ x : ("0",&atoi), ...}
which then calls the right function before actually assigning something.
Or how else can I do to accomplish this?

Better see if you can find some kind of open source solution for
processing a file that is either XML (modern) or <name>=<value> pair, I
am sure that you can find it. GIYF

PS. use boost unfortunately is not an answer since I can't (at least for
     this part of the project

You can't what?

I do not respond to top-posted replies, please don't ask

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