StructCopy

Description

Copies a structure. Copies top-level keys, values, and arrays in the structure by value; copies nested structures by reference.

Returns

A copy of a structure, with the same keys and values; if structure does not exist, throws an exception.

Category

Structure functions

Function syntax

StructCopy(structure)

See also

Structure functions; Structure functions in Using Arrays and Structures in ColdFusion MX Developer's Guide

Parameters

Usage

The following code shows how this function copies a structure that contains a string field, a number field, and a two-dimensional array at the top level:

<cfoutput>
   <cfset assignedCopy = StructNew()>
  <cfset assignedCopy.string = #struct.string#>
   <cfset assignedCopy.number = #struct.number#>
   <cfset assignedCopy.array = ArrayNew(2)>
   <cfset assignedCopy.array[1][1] = #struct.array[1][1]#>
   <cfset assignedCopy.array[1][2] = #sruct.array[1][2]#>
</cfoutput>

The following code shows how StructCopy copies a nested structure:

<cfoutput>
  <cfset assignedCopy.nestedStruct = struct.nestedStruct>
</cfoutput>

To copy a structure entirely by value, use Duplicate.

The following table shows how variables are assigned:

Example

<!--- This code shows assignment by-value and by-reference. --->
// This script creates a structure that StructCopy copies by value. <br> 
<cfscript>
   // Create elements.
   s = StructNew();
   s.array = ArrayNew(2);

   // Assign simple values to original top-level structure fields.
   s.number = 99;
   s.string = "hello tommy";

   // Assign values to original top-level array.
   s.array[1][1] = "one one";
   s.array[1][2] = "one two";
</cfscript>

<!--- Output original structure --->
<hr>
<b>Original Values</b><br>
<cfoutput>
   // Simple values <br>
   s.number = #s.number#<br>
   s.string = #s.string#<br>
   // Array value <br>
   s.array[1][1] = #s.array[1][1]#<br>
   s.array[1][2] = #s.array[1][2]#<br>
</cfoutput>

// Copy this structure to a new structure. <br>
<cfset copied = StructCopy(s)>

<cfscript>
// Change the values of the original structure. <br>
   s.number = 100;
   s.string = "hello tommy (modified)";
   s.array[1][1] = "one one (modified)";
   s.array[1][2] = "one two (modified)";
</cfscript>
<hr>
<b>Modified Original Values</b><br>
<cfoutput>
   // Simple values <br>
   s.number = #s.number#<br>
   s.string = #s.string#<br>
   // Array value <br>
   s.array[1][1] = #s.array[1][1]#<br>
   s.array[1][2] = #s.array[1][2]#<br>
</cfoutput>
<hr>
<b>Copied structure values should be the same as the original.</b><br>
<cfoutput>
   // Simple values <br>
   copied.number = #copied.number#<br>
   copied.string = #copied.string#<br>
   // Array value <br>
   copied.array[1][1] = #copied.array[1][1]#<br>
   copied.array[1][2] = #copied.array[1][2]#<br>
</cfoutput>

// This script creates a structure that StructCopy copies by reference. 
<cfscript>
   // Create elements.
   s = StructNew();
   s.nested = StructNew();
   s.nested.array = ArrayNew(2);
   // Assign simple values to nested structure fields.
   s.nested.number = 99;
   s.nested.string = "hello tommy";
   // Assign values to nested array.
   s.nested.array[1][1] = "one one";
   s.nested.array[1][2] = "one two";
</cfscript>

<!--- Output original structure --->
<hr>
<b>Original Values</b><br>
<cfoutput>
   // Simple values <br>
   s.nested.number = #s.nested.number#<br>
   s.nested.string = #s.nested.string#<br>

   // Array values <br>
   s.nested.array[1][1] = #s.nested.array[1][1]#<br>
   s.nested.array[1][2] = #s.nested.array[1][2]#<br>
</cfoutput>

// Use StructCopy to copy this structure to a new structure. <br>
<cfset copied = StructCopy(s)>
// Use Duplicate to clone this structure to a new structure. <br>
<cfset duplicated = Duplicate(s)>

<cfscript>
// Change the values of the original structure.
   s.nested.number = 100;
   s.nested.string = "hello tommy (modified)";
   s.nested.array[1][1] = "one one (modified)";
   s.nested.array[1][2] = "one two (modified)";
</cfscript>
<hr>
<b>Modified Original Values</b><br>
<cfoutput>
   // Simple values <br>
   s.nested.number = #s.nested.number#<br>
   s.nested.string = #s.nested.string#<br>

   // Array value <br>
   s.nested.array[1][1] = #s.nested.array[1][1]#<br>
   s.nested.array[1][2] = #s.nested.array[1][2]#<br>
</cfoutput>

<hr>
<b>Copied structure values should reflect changes to original.</b><br>
<cfoutput>
   // Simple values <br>
   copied.nested.number = #copied.nested.number#<br>
   copied.nested.string = #copied.nested.string#<br>
   // Array values <br>
   copied.nested.array[1][1] = #copied.nested.array[1][1]#<br>
   copied.nested.array[1][2] = #copied.nested.array[1][2]#<br>
</cfoutput>

<hr>
<b>Duplicated structure values should remain unchanged.</b><br>
<cfoutput>
   // Simple values <br>
   duplicated.nested.number = #duplicated.nested.number#<br>
   duplicated.nested.string = #duplicated.nested.string#<br>
   // Array value <br>
   duplicated.nested.array[1][1] = #duplicated.nested.array[1][1]#<br>
   duplicated.nested.array[1][2] = #duplicated.nested.array[1][2]#<br>
</cfoutput>

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