---
name: "ObjSeq"
section: "3"
platform: "linux"
package: "objpak-dev"
version: "1.1.1-1"
release: "Debian 1.3 (Bo)"
platforms: ["linux"]
url: "https://new.carta.tech/ObjSeq"
---

# ObjSeq(3)

## CLASS

**ObjSeq**

## SUPERCLASS

ObjPak

## DESCRIPTION

Sequences are used to loop or  *sequence*  over a group of objects.  Typically, an  **ObjSeq**  instance is generated by using some method like  **ObjCltn** 's  **eachElement.**   Then, within a loop, one can send  **next**  messages to the sequence until the end is reached (when the  **next**  method returns  **nil** ).  Finally, after using the sequence, you have to free the sequence object.

**Warning**

Using a sequence can lead to problems if, in sequencing over a collection, that collection is modified, e.g., as in the following :

id item;\
 id aSeq;\

aSeq = \[aCol eachElement\];\
 while ((item = \[aSeq next\])) \[aCol add:something\]; // WRONG !!!\
 aSeq = \[aSeq free\];\

You may not modify a group of objects while sequencing over its contents.

## METHOD TYPES

**Creation**

copy\
 free\

**Interrogation**

size\

**Accessing**

next\
 peek\
 previous\
 first\
 last\

**Printing**

printToFile:\

## METHODS

**copy**

\- **copy**

Returns a copy of the sequence.  Can be used independently of the original sequence.

**free**

\- **free**

Frees the receiver, but not the objects in the collection being sequenced over.

**size**

\- (unsigned) **size**

Returns the total number of items in the sequence.

**next**

\- **next**

Returns the next object in the sequence if there is one and advances the sequence.  When it reaches the end of the sequence, returns  **nil.**

**peek**

\- **peek**

Returns the next object in the sequence if there is one, but does not advance the sequence.  When it reaches the end of the sequence, returns  **nil.**

**previous**

\- **previous**

Returns the object that was returned by the last  **next**  message.  If there were no  **next**  messages since the sequence was created, or the sequence is empty, returns  **nil.**   Doesn't affect the current position in the sequence.

**first**

\- **first**

Returns the first object in the sequence, unlesss there are no members in the sequence, in which case it returns  **nil.**   Doesn't affect the current position in the sequence.

**last**

\- **last**

Returns the last object in the sequence, unlesss there are no members in the sequence, in which case it returns  **nil.**   Doesn't affect the current position in the sequence.

**printToFile:**

\- **printToFile:** (FILE \*) *aFile*

Prints a newline separated list of the objects in the sequence to  *aFile* , by sending each individual object a  **printToFile:**  message.  Returns the sequence when there are no more elements left.