What's wrong with Globals?

[Simon HARPER]

So as a newbie, would I be right in thinking that you can call any  
function from the library stack in any other stack, or must the  
library stack be the mainstack. Also you say "put 'in use' at  
startup" do you have to do this via a specific command?


Cheers
Si.

====
Simon Harper
2.44 Kilburn Building
University of Manchester (UK)

Pri: simon.harper at manchester.ac.uk
Alt: sharper at cs.man.ac.uk


On 2 Apr 2007, at 23:20, Mark Smith wrote:

> 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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