What's wrong with Globals?

[Mark Smith]

Well, I'm certainly not going to presume to criticise your method,  
but in the spirit of "you show me yours, I'll show you mine", what I  
tend to do is to have a stack in my apps which is put 'in use' at  
startup, and which has various getters and setters. The actual data  
it returns could be in cps, script locals, text files, databases or  
somewhere on t'internet, the calling handlers don't have to know. So:

answer gcOK() in a handler calls the gcOK() function in my library  
stack which might be

function gcOK
   return "OK?" -- literal
end gcOK

or

function cgOK
   return the okMessage of me -- cp
end gcOK

or

function gcOK
   return sOkMessage -- script local
end gcOK

or

function gcOK
   get URL (http://www.google.com/search?q=OK"
   --parse html and find what you need
   return whatYouFound
end gcOK

etc.

This approach proved very handy indeed recently, when the data  
(retrieved from the web) for one of my apps changed format, but all I  
had to do was re-write a couple of getter functions, the job was  
done, and I felt quite smug.

Script locals are quite a neat way of achieving data-hiding when used  
this way.

Best,

Mark



On 2 Apr 2007, at 23:53, Graham Samuel wrote:

> Forgive me if this conversation has ended, but my internet  
> connection has been in meltdown... just got back on line.
>
> I most frequently use globals because there aren't global  
> constants. I use them very largely for strings containing stuff  
> like error messages or even very simple strings like "OK", so that  
> I can refer to these indirectly in scripts, thus allowing me to  
> switch (human) languages by redefining the globals in just one  
> script of the program. I guess I could have used custom property  
> sets with exactly the same effect, and with the advantage that I  
> wouldn't have to initialise them during the startup of my app, but  
> like many others I didn't understand these when I started, and I  
> tend to re-use stuff I wrote before. I guess there isn't much  
> difference between writing
>
>   answer gcOK  -- 'gcOK' is a global with a string in it.
>
>        and
>
>   answer (the gcOK of stack "allTheConstantStrings") -- 'the gcOK'  
> is a property of some object.
>
> but the second statement seems to have more characters in it, since  
> it involves referring to the object in which the property is  
> stored. If there are a lot of such references, my scripts are going  
> to get longer.
>
> I also use globals when I have a quantity which needs to be used in  
> different scripts in different stacks, i.e globally: a very obvious  
> point, but I really don't see what is wrong with that. I do accept  
> that I have to be disciplined about changing their values. I do use  
> properties (I tend to use these for global status stuff like 'the  
> soundOn of this stack'), parameter-passing and message-passing  
> extensively, but to me globals feel right for quite a lot of things.
>
> I shall now wait for someone to tell me why this is a really wrong- 
> headed approach. I'm always willing to learn - really.
>
> Graham
>
>
> ----------------------------------------
> Graham Samuel / The Living Fossil Co. / UK and France
>
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