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Diffstat (limited to 'doc/syntax/assignment.rdoc')
| -rw-r--r-- | doc/syntax/assignment.rdoc | 16 |
1 files changed, 12 insertions, 4 deletions
diff --git a/doc/syntax/assignment.rdoc b/doc/syntax/assignment.rdoc index a1806e4c48..f45f5bc0ea 100644 --- a/doc/syntax/assignment.rdoc +++ b/doc/syntax/assignment.rdoc @@ -8,6 +8,9 @@ example assigns the number five to the local variable +v+: Assignment creates a local variable if the variable was not previously referenced. +An assignment expression result is always the assigned value, including +{assignment methods}[rdoc-ref:syntax/assignment.rdoc@Assignment+Methods]. + == Local Variable Names A local variable name must start with a lowercase US-ASCII letter or a @@ -104,7 +107,7 @@ Rather than printing "true" you receive a NameError, "undefined local variable or method `a'". Since ruby parses the bare +a+ left of the +if+ first and has not yet seen an assignment to +a+ it assumes you wish to call a method. Ruby then sees the assignment to +a+ and will assume you are referencing a local -method. +variable. The confusion comes from the out-of-order execution of the expression. First the local variable is assigned-to then you attempt to call a nonexistent @@ -159,9 +162,7 @@ Here is an example of instance variable usage: p object1.value # prints "some value" p object2.value # prints "other value" -An uninitialized instance variable has a value of +nil+. If you run Ruby with -warnings enabled, you will get a warning when accessing an uninitialized -instance variable. +An uninitialized instance variable has a value of +nil+. The +value+ method has access to the value set by the +initialize+ method, but only for the same object. @@ -342,6 +343,9 @@ This prints: local_variables: @value: 42 +Note that the value returned by an assignment method is ignored whatever, +since an assignment expression result is always the assignment value. + == Abbreviated Assignment You can mix several of the operators and assignment. To add 1 to an object @@ -397,6 +401,10 @@ assigning. This is similar to multiple assignment: p a # prints [1, 2, 3] + b = *1 + + p b # prints [1] + You can splat anywhere in the right-hand side of the assignment: a = 1, *[2, 3] |