ColdFusion Developer's Guide - Electromanuals.org

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#mycol[2]#
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ColdFusion Developer’s Guide
However, when you make an assignment that requires a simple value, ColdFusion automatically converts the query
column to the value of the first row. For example, the following lines display the name "ben" twice:
#myQuery.Firstname#
#myVar#
Using periods in variable references
ColdFusion uses the period (.) to separate elements of a complex variable such as a structure, query, XML document
object, or external object, as in MyStruct.KeyName. A period also separates a variable scope identifier from the
variable name, as in Variables.myVariable or CGI.HTTP_COOKIE.
With the exception of Cookie and Client scope variables, which must always be simple variable types, you cannot
normally include periods in simple variable names. However, ColdFusion makes some exceptions that accommodate
legacy and third-party code that does not conform to this requirement.
For more information, see “About scopes” on page 42, “Using Arrays and Structures” on page 68, and “Using XML
and WDDX” on page 865.
Understanding variables and periods
The following descriptions use a sample variable named MyVar.a.b to explain how ColdFusion uses periods when
getting and setting the variable value.
Getting a variable
ColdFusion can correctly get variable values even if the variable name includes a period. For example, the following
set of steps shows how ColdFusion gets MyVar.a.b, as in or IsDefined(myVar.a.b):
1 Looks for myVar in an internal table of names (the symbol table).
2 If myVar is the name of a complex object, including a scope, looks for an element named a in the object.
If myVar is not the name of a complex object, checks whether myVar.a is the name of a complex object and skips
step 3.
3 If myVar is the name of a complex object, checks whether a is a complex object.
4 If a or myVar.a is the name of a complex object, checks whether b is the name of a simple variable, and returns
the value of b.
If myVar is a complex object but a is not a complex object, checks whether a.b is the name of a simple variable
and returns its value.
If myVar.a is not a complex object, checks whether myVar.a.b is the name of a simple variable and returns its
value.
This way, ColdFusion correctly resolves the variable name and can get its value.
You can also use array notation to get a simple variable with a name that includes periods. In this form of array
notation, you use the scope name (or the complex variable that contains the simple variable) as the “array” name.
You put the simple variable name, in single- or double-quotation marks, inside the square brackets.
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