FileManager Functional Organization - Expected Use

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As an aid to understanding the FileManager class, it is useful to organize the various FileManager methods into two large categories according to their expected use--the primary interface and the virtual methods. This organization reflects what we believe is typical use of the FileManager methods.

Non-Virtual Methods

The Non-Virtual Methods, which you are likely to call fairly routinely from your program, can be further divided into three categories:

Housekeeping (one-time) Use:

 

Init

initialize the FileManager object

 

Kill

terminate the FileManager object

Mainstream Use:

 

Open (v)

open the file

 

TryOpen

open the file

 

Next

get the next record in sequence

 

TryNext

get the next record in sequence

 

Previous

get the previous record in sequence

 

TryPrevious

get the previous record in sequence

 

Fetch

get a specific record by key value

 

TryFetch

get a specific record by key value

 

Position

return the unique position of the current record

 

TryReget

get a specific record by unique position

 

PrimeAutoInc (v)

prepare an autoincremented record for adding

 

Insert

add a new record

 

TryInsert

add a new record

 

CancelAutoInc (v)

restore file to its pre-PrimeAutoInc state

 

Update

change the current record

 

TryUpdate

change the current record

 

Close (v)

close the file

(v)These methods are also Virtual.

Occasional Use:

 

ClearKey

clear a range of key component fields

 

SetKey

make a specific key current for other methods

 

KeyToOrder

return ORDER expression equal to specified key

 

GetComponents

return the number of components of a key

 

GetField

return a reference to a key component

 

GetFieldName

return the field name of a key component

 

GetEOF

return current end of file status

 

GetError

return the current error ID

 

SetError

save the current error state

 

GetName

return the name of the file

 

SetName

set the file name

 

SetOpenMode

set the file open mode

 

SaveBuffer

save the current record buffer contents

 

RestoreBuffer

restore previously saved buffer contents

 

SaveFile

save the current file state

 

RestoreFile

restore a previously saved file state

 

UseFile

open a LazyOpen file

 

AddKey

describe the soft KEYs

Virtual Methods

Typically, with the possible exception of Open and Close, you will not call these methods directly--the Non-Virtual Methods call them. However, we anticipate you will often want to override these methods, and because they are virtual, they are very easy to override. These methods do provide reasonable default behavior in case you do not want to override them.

 

Open

open the file

 

BindFields

BIND all the file's fields

 

PrimeAutoInc

prepare an autoincremented record for adding

 

TryPrimeAutoInc

prepare an autoincremented record for adding

 

CancelAutoInc

restore file to its pre-PrimeAutoInc state

 

EqualBuffer

detect record buffer changes

 

PrimeFields

prepare record fields for adding

 

PrimeRecord

prepare a record for adding

 

Throw

process an error

 

ThrowMessage

set custom message text then process an error

 

ValidateField

validate a specific field in the current buffer

 

ValidateFields

validate a range of fields in the current buffer

 

ValidateRecord

validate all fields in the current buffer

 

Close

close the file