Expose sheet title maximum length as Worksheet::SHEET_TITLE_MAXIMUM_LENGTH

Closes #482

Author: cwild

CHANGELOG.md

@@ -11,6 +11,7 @@ and this project adheres to [Semantic Versioning](http://semver.org/).
 ### Added
 
 - Support to read Xlsm templates with form elements, macros, printer settings, protected elements and back compatibility drawing, and save result without losing important elements of document - [#435](https://github.com/PHPOffice/PhpSpreadsheet/issues/435)
+- Expose sheet title maximum length as `Worksheet::SHEET_TITLE_MAXIMUM_LENGTH` - [#482](https://github.com/PHPOffice/PhpSpreadsheet/issues/482)
 
 ### Fixed
 

src/PhpSpreadsheet/Worksheet/Worksheet.php

@@ -37,6 +37,13 @@ class Worksheet implements IComparable
     const SHEETSTATE_HIDDEN = 'hidden';
     const SHEETSTATE_VERYHIDDEN = 'veryHidden';
 
+    /**
+     * Maximum 31 characters allowed for sheet title.
+     *
+     * @var int
+     */
+    const SHEET_TITLE_MAXIMUM_LENGTH = 31;
+
     /**
      * Invalid characters in sheet title.
      *
@@ -434,9 +441,9 @@ private static function checkSheetCodeName($pValue)
             throw new Exception('Invalid character found in sheet code name');
         }
 
-        // Maximum 31 characters allowed for sheet title
-        if ($CharCount > 31) {
-            throw new Exception('Maximum 31 characters allowed in sheet code name.');
+        // Enforce maximum characters allowed for sheet title
+        if ($CharCount > self::SHEET_TITLE_MAXIMUM_LENGTH) {
+            throw new Exception('Maximum ' . self::SHEET_TITLE_MAXIMUM_LENGTH . ' characters allowed in sheet code name.');
         }
 
         return $pValue;
@@ -458,9 +465,9 @@ private static function checkSheetTitle($pValue)
             throw new Exception('Invalid character found in sheet title');
         }
 
-        // Maximum 31 characters allowed for sheet title
-        if (Shared\StringHelper::countCharacters($pValue) > 31) {
-            throw new Exception('Maximum 31 characters allowed in sheet title.');
+        // Enforce maximum characters allowed for sheet title
+        if (Shared\StringHelper::countCharacters($pValue) > self::SHEET_TITLE_MAXIMUM_LENGTH) {
+            throw new Exception('Maximum ' . self::SHEET_TITLE_MAXIMUM_LENGTH . ' characters allowed in sheet title.');
         }
 
         return $pValue;