php global variables with variable names

Question

I am trying to have a function that among other things declares global variables based on a variable that i give it. the part that fails is making the variables global

function setGlobalVariable($name) {

    global $name, $arrayname_{$name};
}

any idea? thanks :)

why would you want to pollute the global namespace with variables? — bcosca
– bcosca, Commented Nov 23, 2010 at 11:27
Only one: Avoid global variables. Usually they are a powerful source of troubles (and you don't need them). — Eineki
– Eineki, Commented Nov 23, 2010 at 11:29
I agree with you all about the poor use of Global variables. What i am trying to do is write a function that does MSQL query and returns all the variables needed. Not only the array of the query but also mysql_query() & mysql_num_rows() for other uses such as a do loop to display the results. I would love to have a better way to do this but I am not an expert. Any suggestions? — salmane
– salmane, Commented Nov 23, 2010 at 11:36
Then create dependent functions that have arguments for passing results to and from other functions, instead of using the global namespace as a temporary holding area - the latter is like throwing your garbage on the street expecting that someone will pick it up later — bcosca
– bcosca, Commented Nov 23, 2010 at 11:44

ThiefMaster · Accepted Answer · 2010-11-23 11:30:51Z

6

Really, stop messing with global variables that way.

Anywaym here's your solution if you really want to do that:

function setGlobalVariable($name) {
    $GLOBALS['arrayname_' . $name] = 'yourvalue';
}

answered Nov 23, 2010 at 11:30

ThiefMaster

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jwueller · Accepted Answer · 2010-11-23 11:31:19Z

3

You should not do that. Global variables are in general a sign of poor design. What is it that you are trying to achieve? I am sure that there is a better solution. Besides that, global does not work like that. global makes other variables outside your function locally available. Use $_GLOBAL to create globals.

answered Nov 23, 2010 at 11:31

jwueller

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Yeroon · Accepted Answer · 2010-11-23 12:06:17Z

1

Take a look at the Registry Pattern (http://martinfowler.com/eaaCatalog/registry.html).

A well-known object that other objects can use to find common objects and services.

There are various PHP implementations, for example Zend_Registry: http://framework.zend.com/manual/en/zend.registry.html

answered Nov 23, 2010 at 12:06

Yeroon

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Chris Heald · Accepted Answer · 2010-11-23 11:31:30Z

0

You're almost right, but not quite; a variable variable takes the form of ${"name"}, so what you're looking for is something like global ${"arrayname_$name"};.

http://www.reddit.com/r/programming/comments/dst56/today_i_learned_about_php_variable_variables/c12np38 is fascinating reading on the topic, if you feel so inclined.

It's likely a terrible idea, though, and if you're resorting to that sort of thing, it's a good indication that your code may be poorly designed. Consider refactoring it (for example, to keep a single known array that your other arrays are kept in, and may be referenced by key.)

answered Nov 23, 2010 at 11:31

Chris Heald

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