CLASS vlt.file.fileobj¶
vlt.file.fileobj - a Matlab binary file object; an interface to fopen, fread, fwrite, fseek, fclose, ftell
This is an object interface to fopen, fread, fwrite, fseek, fclose, and ftell. Why do this?
One could imagine one day separating the process of reading and writing a data stream from the file
system. For example, one could write to GRIDFS by overriding these functions, and the user's code
would never have to know.
Superclasses¶
handle
Properties¶
| Property | Description |
|---|---|
| fullpathfilename | |
| fid | |
| permission | |
| machineformat | 'big-endian' or 'little-endian' |
Methods¶
| Method | Description |
|---|---|
| addlistener | ADDLISTENER Add listener for event. |
| delete | delete a FILEOBJ_OBJ, closing file first if need be |
| eq | == (EQ) Test handle equality. |
| fclose | close a FILEOBJ |
| feof | test to see if a FILEOBJ is at END-OF-FILE |
| ferror | return the last file error message for FILEOBJ |
| fgetl | get a line from a FILEOBJ |
| fgets | get a line from a FILEOBJ |
| fileobj | create a new binary file object |
| fileparts | return filename parts for the file associated with FILEOBJ |
| findobj | FINDOBJ Find objects matching specified conditions. |
| findprop | FINDPROP Find property of MATLAB handle object. |
| fopen | open a FILEOBJ |
| fprintf | print data to a FILEOBJ_OBJ |
| fread | read data from a FILEOBJ |
| frewind | 'rewind' a FILEOBJ back to the beginning |
| fscanf | scan data from a FILEOBJ_OBJ |
| fseek | seek to a location within a FILEOBJ |
| ftell | find current location within a FILEOBJ |
| fwrite | write data to a FILEOBJ |
| ge | >= (GE) Greater than or equal relation for handles. |
| gt | > (GT) Greater than relation for handles. |
| isvalid | ISVALID Test handle validity. |
| le | <= (LE) Less than or equal relation for handles. |
| listener | LISTENER Add listener for event without binding the listener to the source object. |
| lt | < (LT) Less than relation for handles. |
| ne | ~= (NE) Not equal relation for handles. |
| notify | NOTIFY Notify listeners of event. |
| setproperties | set the properties of a FILEOBJ |
Methods help¶
addlistener - ADDLISTENER Add listener for event.
el = ADDLISTENER(hSource, Eventname, callbackFcn) creates a listener
for the event named Eventname. The source of the event is the handle
object hSource. If hSource is an array of source handles, the listener
responds to the named event on any handle in the array. callbackFcn
is a function handle that is invoked when the event is triggered.
el = ADDLISTENER(hSource, PropName, Eventname, Callback) adds a
listener for a property event. Eventname must be one of
'PreGet', 'PostGet', 'PreSet', or 'PostSet'. Eventname can be
a string scalar or character vector. PropName must be a single
property name specified as string scalar or character vector, or a
collection of property names specified as a cell array of character
vectors or a string array, or as an array of one or more
meta.property objects. The properties must belong to the class of
hSource. If hSource is scalar, PropName can include dynamic
properties.
For all forms, addlistener returns an event.listener. To remove a
listener, delete the object returned by addlistener. For example,
delete(el) calls the handle class delete method to remove the listener
and delete it from the workspace.
ADDLISTENER binds the listener's lifecycle to the object that is the
source of the event. Unless you explicitly delete the listener, it is
destroyed only when the source object is destroyed. To control the
lifecycle of the listener independently from the event source object,
use listener or the event.listener constructor to create the listener.
See also LISTENER, EVENT.LISTENER, VLT.FILE.FILEOBJ, NOTIFY, DELETE, META.PROPERTY, EVENTS
Help for vlt.file.fileobj/addlistener is inherited from superclass handle
delete - delete a FILEOBJ_OBJ, closing file first if need be
DELETE(FILEOBJ_OBJ)
Deletes the handle FILEOBJ_OBJ. If the file (FILEOBJ_OBJ.fid) is open,
it is closed first.
See also: HANDLE/DELETE, FILEOBJ/FCLOSE
eq - == (EQ) Test handle equality.
Handles are equal if they are handles for the same object.
H1 == H2 performs element-wise comparisons between handle arrays H1 and
H2. H1 and H2 must be of the same dimensions unless one is a scalar.
The result is a logical array of the same dimensions, where each
element is an element-wise equality result.
If one of H1 or H2 is scalar, scalar expansion is performed and the
result will match the dimensions of the array that is not scalar.
TF = EQ(H1, H2) stores the result in a logical array of the same
dimensions.
See also VLT.FILE.FILEOBJ, VLT.FILE.FILEOBJ/GE, VLT.FILE.FILEOBJ/GT, VLT.FILE.FILEOBJ/LE, VLT.FILE.FILEOBJ/LT, VLT.FILE.FILEOBJ/NE
Help for vlt.file.fileobj/eq is inherited from superclass handle
fclose - close a FILEOBJ
FILEOBJ_OBJ = FCLOSE(FILEOBJ_OBJ)
Close a file associated with a FILEOBJ.
Attempt to close the file and then set FILEOBJ_OBJ.fid to -1.
feof - test to see if a FILEOBJ is at END-OF-FILE
B = FEOF(FILEOBJ_OBJ)
Returns 1 if FILEOBJ_OBJ is at its end of file, 0 otherwise.
See also: FSEEK, FILEOBJ/FSEEK, FTELL
ferror - return the last file error message for FILEOBJ
[MESSAGE, ERRORNUM] = FERROR(FILEOBJ_OBJ, COMMAND)
Return the most recent file error MESSAGE and ERRORNUM for
the file associated with FERROR.
fgetl - get a line from a FILEOBJ
TLINE = FGETL(FILEOBJ_OBJ)
Returns the next line (not including NEWLINE character) just like FGETL.
See also: FGETL
fgets - get a line from a FILEOBJ
TLINE = FGETS(FILEOBJ_OBJ, [NCHAR])
Returns the next line (including NEWLINE character) just like FGETS.
See also: FGETS
fileobj - create a new binary file object
FILEOBJ_OBJ = FILEOBJ(...)
Creates an empty FILEOBJ object. If FILENAME is provided,
then the filename is stored.
Documentation for vlt.file.fileobj/fileobj
doc vlt.file.fileobj
fileparts - return filename parts for the file associated with FILEOBJ
[PATHSTR,NAME,EXT] = FILEPARTS(FILEOBJ_OBJ)
Returns FILEPARTS of the 'fullpathfilename' field of FILEOBJ.
findobj - FINDOBJ Find objects matching specified conditions.
The FINDOBJ method of the HANDLE class follows the same syntax as the
MATLAB FINDOBJ command, except that the first argument must be an array
of handles to objects.
HM = FINDOBJ(H, <conditions>) searches the handle object array H and
returns an array of handle objects matching the specified conditions.
Only the public members of the objects of H are considered when
evaluating the conditions.
See also FINDOBJ, VLT.FILE.FILEOBJ
Help for vlt.file.fileobj/findobj is inherited from superclass handle
findprop - FINDPROP Find property of MATLAB handle object.
p = FINDPROP(H,PROPNAME) finds and returns the META.PROPERTY object
associated with property name PROPNAME of scalar handle object H.
PROPNAME can be a string scalar or character vector. It can be the
name of a property defined by the class of H or a dynamic property
added to scalar object H.
If no property named PROPNAME exists for object H, an empty
META.PROPERTY array is returned.
See also VLT.FILE.FILEOBJ, VLT.FILE.FILEOBJ/FINDOBJ, DYNAMICPROPS, META.PROPERTY
Help for vlt.file.fileobj/findprop is inherited from superclass handle
fopen - open a FILEOBJ
FILEOBJ_OBJ = FOPEN(FILEOBJ_OBJ, [ , PERMISSION], [MACHINEFORMAT],[FILENAME])
Opens the file associated with a FILEOBJ_OBJ object. If FILENAME, PERMISSION,
and MACHINEFORMAT are given, then those variables of FILEOBJ_OBJ are updated. If they
are not given, then the existing values in the FILEOBJ_OBJ are used.
Note that the order of the input arguments differs from FOPEN, so that the object
can be called in place of an FID (e.g., fid=fopen(myvariable), where myvariable is
either a file name or a FILEOBJ object).
If the operation is successful, then FILEOBJ_OBJ.fid is greater than 3. Otherwise,
FILEOBJ_OBJ.fid is -1.
See also: FOPEN, FILEOBJ/FCLOSE, FCLOSE
fprintf - print data to a FILEOBJ_OBJ
[COUNT] = FPRINTF(FID,FORMAT,A, ...)
Call FPRINTF (see FPRINTF for inputs) for the file associated with
FILEOBJ_OBJ.
fread - read data from a FILEOBJ
COUNT = FWRITE(FILEOBJ_OBJ, COUNT, [PRECISION], [SKIP], [MACHINEFORMAT])
Attempts to read COUNT elements with resolution PRECISION. If PRECISION is not
provided, then 'char' is assumed. If SKIP is provided, then SKIP is in number of bytes, unless
PRECISION is in bits, in which case SKIP is in bits. MACHINEFORMAT is the machine format to use.
See FREAD for a full description of these input arguments.
See also: FREAD
frewind - 'rewind' a FILEOBJ back to the beginning
FREWIND(FILEOBJ_OBJ)
Seeks to the beginning of the file.
See also: FSEEK, FILEOBJ/FSEEK, FTELL
fscanf - scan data from a FILEOBJ_OBJ
[A,COUNT] = FSCANF(FID,FORMAT,[SIZEA])
Call FSCANF (see FSCANF for inputs) for the file associated with
FILEOBJ_OBJ.
fseek - seek to a location within a FILEOBJ
B = FSEEK(FILEOBJ_OBJ, OFFSET, REFERENCE)
Seeks the file to the location OFFSET (in bytes) relative to
REFERENCE. REFERENCE can be
'bof' or -1 Beginning of file
'cof' or 0 Current position in file
'eof' or 1 End of file
B is 0 on success and -1 on failure.
See also: FSEEK, FILEOBJ/FTELL
ftell - find current location within a FILEOBJ
LOCATION = FTELL(FILEOBJ_OBJ)
Returns the current location (in bytes) relative to the beginning of the
file. If the query fails, -1 is returned.
See also: FSEEK, FILEOBJ/FSEEK, FTELL
fwrite - write data to a FILEOBJ
COUNT = FWRITE(FILEOBJ_OBJ, DATA, [PRECISION], [SKIP], [MACHINEFORMAT])
Attempts to write DATA elements with resolution PRECISION. If PRECISION is not
provided, then 'char' is assumed. If SKIP is provided, then SKIP is in number of bytes, unless
PRECISION is in bits, in which case SKIP is in bits. MACHINEFORMAT is the machine format to use.
See FWRITE for a full description of these input arguments.
See also: FWRITE
ge - >= (GE) Greater than or equal relation for handles.
H1 >= H2 performs element-wise comparisons between handle arrays H1 and
H2. H1 and H2 must be of the same dimensions unless one is a scalar.
The result is a logical array of the same dimensions, where each
element is an element-wise >= result.
If one of H1 or H2 is scalar, scalar expansion is performed and the
result will match the dimensions of the array that is not scalar.
TF = GE(H1, H2) stores the result in a logical array of the same
dimensions.
See also VLT.FILE.FILEOBJ, VLT.FILE.FILEOBJ/EQ, VLT.FILE.FILEOBJ/GT, VLT.FILE.FILEOBJ/LE, VLT.FILE.FILEOBJ/LT, VLT.FILE.FILEOBJ/NE
Help for vlt.file.fileobj/ge is inherited from superclass handle
gt - > (GT) Greater than relation for handles.
H1 > H2 performs element-wise comparisons between handle arrays H1 and
H2. H1 and H2 must be of the same dimensions unless one is a scalar.
The result is a logical array of the same dimensions, where each
element is an element-wise > result.
If one of H1 or H2 is scalar, scalar expansion is performed and the
result will match the dimensions of the array that is not scalar.
TF = GT(H1, H2) stores the result in a logical array of the same
dimensions.
See also VLT.FILE.FILEOBJ, VLT.FILE.FILEOBJ/EQ, VLT.FILE.FILEOBJ/GE, VLT.FILE.FILEOBJ/LE, VLT.FILE.FILEOBJ/LT, VLT.FILE.FILEOBJ/NE
Help for vlt.file.fileobj/gt is inherited from superclass handle
isvalid - ISVALID Test handle validity.
TF = ISVALID(H) performs an element-wise check for validity on the
handle elements of H. The result is a logical array of the same
dimensions as H, where each element is the element-wise validity
result.
A handle is invalid if it has been deleted or if it is an element
of a handle array and has not yet been initialized.
See also VLT.FILE.FILEOBJ, VLT.FILE.FILEOBJ/DELETE
Help for vlt.file.fileobj/isvalid is inherited from superclass handle
le - <= (LE) Less than or equal relation for handles.
Handles are equal if they are handles for the same object. All
comparisons use a number associated with each handle object. Nothing
can be assumed about the result of a handle comparison except that the
repeated comparison of two handles in the same MATLAB session will
yield the same result. The order of handle values is purely arbitrary
and has no connection to the state of the handle objects being
compared.
H1 <= H2 performs element-wise comparisons between handle arrays H1 and
H2. H1 and H2 must be of the same dimensions unless one is a scalar.
The result is a logical array of the same dimensions, where each
element is an element-wise >= result.
If one of H1 or H2 is scalar, scalar expansion is performed and the
result will match the dimensions of the array that is not scalar.
TF = LE(H1, H2) stores the result in a logical array of the same
dimensions.
See also VLT.FILE.FILEOBJ, VLT.FILE.FILEOBJ/EQ, VLT.FILE.FILEOBJ/GE, VLT.FILE.FILEOBJ/GT, VLT.FILE.FILEOBJ/LT, VLT.FILE.FILEOBJ/NE
Help for vlt.file.fileobj/le is inherited from superclass handle
listener - LISTENER Add listener for event without binding the listener to the source object.
el = LISTENER(hSource, Eventname, callbackFcn) creates a listener
for the event named Eventname. The source of the event is the handle
object hSource. If hSource is an array of source handles, the listener
responds to the named event on any handle in the array. callbackFcn
is a function handle that is invoked when the event is triggered.
el = LISTENER(hSource, PropName, Eventname, callback) adds a
listener for a property event. Eventname must be one of
'PreGet', 'PostGet', 'PreSet', or 'PostSet'. Eventname can be a
string sclar or character vector. PropName must be either a single
property name specified as a string scalar or character vector, or
a collection of property names specified as a cell array of character
vectors or a string array, or as an array of one ore more
meta.property objects. The properties must belong to the class of
hSource. If hSource is scalar, PropName can include dynamic
properties.
For all forms, listener returns an event.listener. To remove a
listener, delete the object returned by listener. For example,
delete(el) calls the handle class delete method to remove the listener
and delete it from the workspace. Calling delete(el) on the listener
object deletes the listener, which means the event no longer causes
the callback function to execute.
LISTENER does not bind the listener's lifecycle to the object that is
the source of the event. Destroying the source object does not impact
the lifecycle of the listener object. A listener created with LISTENER
must be destroyed independently of the source object. Calling
delete(el) explicitly destroys the listener. Redefining or clearing
the variable containing the listener can delete the listener if no
other references to it exist. To tie the lifecycle of the listener to
the lifecycle of the source object, use addlistener.
See also ADDLISTENER, EVENT.LISTENER, VLT.FILE.FILEOBJ, NOTIFY, DELETE, META.PROPERTY, EVENTS
Help for vlt.file.fileobj/listener is inherited from superclass handle
lt - < (LT) Less than relation for handles.
H1 < H2 performs element-wise comparisons between handle arrays H1 and
H2. H1 and H2 must be of the same dimensions unless one is a scalar.
The result is a logical array of the same dimensions, where each
element is an element-wise < result.
If one of H1 or H2 is scalar, scalar expansion is performed and the
result will match the dimensions of the array that is not scalar.
TF = LT(H1, H2) stores the result in a logical array of the same
dimensions.
See also VLT.FILE.FILEOBJ, VLT.FILE.FILEOBJ/EQ, VLT.FILE.FILEOBJ/GE, VLT.FILE.FILEOBJ/GT, VLT.FILE.FILEOBJ/LE, VLT.FILE.FILEOBJ/NE
Help for vlt.file.fileobj/lt is inherited from superclass handle
ne - ~= (NE) Not equal relation for handles.
Handles are equal if they are handles for the same object and are
unequal otherwise.
H1 ~= H2 performs element-wise comparisons between handle arrays H1
and H2. H1 and H2 must be of the same dimensions unless one is a
scalar. The result is a logical array of the same dimensions, where
each element is an element-wise equality result.
If one of H1 or H2 is scalar, scalar expansion is performed and the
result will match the dimensions of the array that is not scalar.
TF = NE(H1, H2) stores the result in a logical array of the same
dimensions.
See also VLT.FILE.FILEOBJ, VLT.FILE.FILEOBJ/EQ, VLT.FILE.FILEOBJ/GE, VLT.FILE.FILEOBJ/GT, VLT.FILE.FILEOBJ/LE, VLT.FILE.FILEOBJ/LT
Help for vlt.file.fileobj/ne is inherited from superclass handle
notify - NOTIFY Notify listeners of event.
NOTIFY(H, eventname) notifies listeners added to the event named
eventname for handle object array H that the event is taking place.
eventname can be a string scalar or character vector.
H is the array of handles to the event source objects, and 'eventname'
must be a character vector.
NOTIFY(H,eventname,ed) provides a way of encapsulating information
about an event which can then be accessed by each registered listener.
ed must belong to the EVENT.EVENTDATA class.
See also VLT.FILE.FILEOBJ, VLT.FILE.FILEOBJ/ADDLISTENER, VLT.FILE.FILEOBJ/LISTENER, EVENT.EVENTDATA, EVENTS
Help for vlt.file.fileobj/notify is inherited from superclass handle
setproperties - set the properties of a FILEOBJ
FILEOBJ_OBJ = SETPROPERTIES(FILEOBJ_OBJ, 'PROPERTY1',VALUE1, ...)
Sets the properties of a FILEOBJ with name/value pairs.
Properties are:
fullpathfilename; % the full path file name of the file
fid; % The Matlab file identifier
permission; % The file permission
machineformat % big-endian ('b'), little-endian ('l'), or native ('n')