Difference between revisions of "Ruby Variable Scope"
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(→What is Variable Scope?) |
(→What is Variable Scope?) |
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<tr style="background:#efefef;"> | <tr style="background:#efefef;"> | ||
<th>Name Begins With<th>Variable Scope</th> | <th>Name Begins With<th>Variable Scope</th> | ||
| − | <tr><td><code>$</code> </td><td> | + | <tr><td><code>$</code> </td><td>A global variable </td></tr> |
<tr><td> | <tr><td> | ||
<code>@</code> </td><td> An instance variable </td></tr> | <code>@</code> </td><td> An instance variable </td></tr> | ||
| Line 16: | Line 16: | ||
<code>[A-Z]</code> </td><td>A constant</td></tr> | <code>[A-Z]</code> </td><td>A constant</td></tr> | ||
<tr><td> | <tr><td> | ||
| − | <code>@@</code></td><td>A class variable</td>/tr></table> | + | <code>@@</code></td><td>A class variable</td></tr></table> |
In addition, Ruby has two ''pseudo-variables'' which cannot be assigned values. These are ''nil'' which is assigned to uninitialized variables and ''self'' which refers to the currently executing object. | In addition, Ruby has two ''pseudo-variables'' which cannot be assigned values. These are ''nil'' which is assigned to uninitialized variables and ''self'' which refers to the currently executing object. | ||
Revision as of 18:44, 15 November 2007
Now that we have covered the basics of variables in Ruby the next task is to explain Ruby variable scope.
What is Variable Scope?
Scope defines where in a program a variable is accessible. Ruby has four types of variable scope, local, global, instance and class. In addition, Ruby has one constant type. Each variable type is declared by using a special character at the start of the variable name as outlined in the following table.
| Name Begins With | Variable Scope |
|---|---|
$ | A global variable |
@ | An instance variable |
[a-z] or _ | A local variable |
[A-Z] | A constant |
@@ | A class variable |
In addition, Ruby has two pseudo-variables which cannot be assigned values. These are nil which is assigned to uninitialized variables and self which refers to the currently executing object.
