Editing Object REXX (section)

=== Utility classes ===
Utility classes are a collection of 31 classes that provide implementations for common tasks. The <code>MutableBuffer</code> class enables greater efficiency in string operations such as concatenation, as no new object needs to be assigned. The <code>File</code> class provides methods for listing files in a directory or retrieving information about files and directories.<ref name=":2" /><syntaxhighlight lang="oorexx" style="background-color: #ffffff; !important" line="1">
FileObj = .File~new("~/someFolder/") /* create file object for folder   */
FileArr = FileObj~ListFiles          /* retrieve array of files         */

do FilePath over FileArr             /* iterate over the array items    */
    say FilePath                     /* output: FilePath item           */
end
</syntaxhighlight>The <code>DateTime</code> or <code>TimeSpan</code> classes support the retrieval and formatting of a date, time or timestamp in various formats and enable arithmetic operations between them. Several Comparator classes facilitate sorting for built-in classes such as File, DateTime and others. The class <code>Supplier</code> and its subclass <code>StreamSupplier</code> enable the enumeration of an items collection together with an indexes collection. The <code>Validate</code> class provides methods that can be used to check whether given arguments are of the correct class and type, or within a numerical range. A <code>VariableReference</code> instance maintains a reference, while a <code>WeakReference</code> instance creates a reference to another object that is not pinned.<ref name=":2" />

A [[regular expression]] is a pattern that can be used to match strings. To increase the readability of patterns in the code, the <code>RegularExpression</code> class allows the use of symbolic names encapsulated with colons (<code>:</code>) for common sets. For instance, matching a string containing only letters typically described as <code>[A-Za-z]</code> can be abbreviated using <code>[:alpha:]</code>.<ref name=":2" />

Other classes help to obtain information about the context of the currently executed code (<code>RexxContext</code>), the Rexx language or the executing platform (<code>RexxInfo</code>) and execution specifics (<code>StackFrame</code>) via environment symbols. The <code>Buffer</code> and <code>Pointer</code> classes are specifically designed to support writing methods and function in native code using the C/C++ APIs. <code>Alarm</code> and <code>Ticker</code> classes provide notification functions and <code>EventSempahore</code> and <code>MutexSempahore</code> classes implement synchronization mechanisms for multi-threading activities. The <code>Monitor</code> class enables messages to be forwarded to various target objects and the <code>RexxQueue</code> class provides object-like access to external Rexx data queues.<ref name=":2" />