Reducing the number of types of errors returned

pdf/core/utils.go

@@ -188,8 +188,7 @@ func GetString(obj PdfObject) (string, error) {
 	if s, ok := obj.(*PdfObjectString); ok {
 		return string(*s), nil
 	}
-	err := errors.New("Not a string")
-	return "", err
+	return "", ErrTypeCheck
 }
 
 // GetStringBytes returns the bytes represented by `obj` if `obj` is a PdfObjectString or an error if it isn't.
@@ -197,8 +196,7 @@ func GetStringBytes(obj PdfObject) ([]byte, error) {
 	if s, ok := obj.(*PdfObjectString); ok {
 		return []byte(*s), nil
 	}
-	err := errors.New("Not a string")
-	return []byte{}, err
+	return []byte{}, ErrTypeCheck
 }
 
 // GetName returns the string represented by `obj` if `obj` is a PdfObjectName or an error if it isn't.
@@ -206,8 +204,7 @@ func GetName(obj PdfObject) (string, error) {
 	if s, ok := obj.(*PdfObjectName); ok {
 		return string(*s), nil
 	}
-	err := errors.New("Not a name")
-	return "", err
+	return "", ErrTypeCheck
 }
 
 // GetInteger returns the int represented by `obj` if `obj` is a PdfObjectInteger or an error if it isn't.
@@ -215,8 +212,7 @@ func GetInteger(obj PdfObject) (int, error) {
 	if i, ok := obj.(*PdfObjectInteger); ok {
 		return int(*i), nil
 	}
-	err := errors.New("Not an integer")
-	return 0, err
+	return 0, ErrTypeCheck
 }
 
 // GetArray returns the slice of PdfObjects represented by `obj` if `obj` is a PdfObjectArray or an
@@ -225,8 +221,7 @@ func GetArray(obj PdfObject) ([]PdfObject, error) {
 	if s, ok := obj.(*PdfObjectArray); ok {
 		return []PdfObject(*s), nil
 	}
-	err := errors.New("Not an array")
-	return nil, err
+	return nil, ErrTypeCheck
 }
 
 // EqualObjects returns true if `obj1` and `obj2` have the same contents.