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Sets Command-Window tab completion for specified functions & arguments: types and custom strings

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Argument tab-completion occur when the user presses the <Tab> key following the function name in the Command Window. The list of available/possible arguments is then presented in a popup window.

TABCOMPLETE modifies the [matlabroot '/toolbox/local/TC.xml'] file to set/unset the tab-completion definition of the specified function. Note: changes take effect only after a Matlab restart.

TABCOMPLETE(funcName, argType1, argType2, ...) sets the tab-completion list for function arguments 1, 2, etc. argType can be one of these pre-defined keywords:
- 'var' - list of current workspace variables
- 'fun' - list of accessible functions
- 'subfun' - list of accessible sub-functions
- 'dir' - list of accessible folders (directories)
- 'file' - list of accessible files (of any type)
- 'mfile' - list of accessible *.m files (Matlab functions)
- 'matfile' - list of accessible *.mat files (Matlab data)
- 'figfile' - list of accessible *.fig files (figures)
- 'mdlfile' - list of accessible *.mdl files (Simulink models)
- 'mcospkg' - list of accessible MCOS class packages (R2010a+)
- 'mcosclass' - list of accessible MCOS classes (R2010a+)
- 'messageid' - list of accessible error/warning message IDs (R2011b+)
- (if none of the above is specified, 'subfun' is set automatically)
And in addition to the pre-defined kewords:
- additional string value(s) that will be added to the pop-up list

Multiple types for the same argument can be specified:
- as a cell array - example: {'var','file','on','off'}
- as a space-separated string - example: 'var file on off'

The last argType specified will apply for all subsequent arguments. The last argType may be '' (empty string) to indicate the end of tab-completed args. The last argType does *NOT* accept additional string values like the rest of the arguments.

TABCOMPLETE(funcName,'') removes all arg tab-completions for funcName (this is an immediate corollary of the previous paragraph).

definitions=TABCOMPLETE (without any arguments) returns a structure array listing all the current tab-completion definitions.

definitions=TABCOMPLETE(funcName) returns a structure listing the tab-completion definition for the specified function (if existing).

definitions=TABCOMPLETE(...) returns a structure array listing all tab-completion definitions BEFORE their modification by TABCOMPLETE.

tabcomplete('addpath','dir') % sets multiple folder completions
tabcomplete('edit','file fun') % sets multiple file/func completions
tabcomplete('cd','dir','') % sets a single-arg folder completion
=> *.mat followed by multiple variable-names or '-struct'/'-regexp'
tabcomplete('myFunc','') % removes myFunc's arg tab-completions
defs = tabcomplete('cd') % returns 'cd' function's tab-completions
defs = tabcomplete % returns all currently-defined tab-completions

This code heavily relies on undocumented and unsupported Matlab functionality. It works on Matlab 7+, but use at your own risk!

Technical explanation:
A technical explanation of the code in this utility can be found on

Bugs and suggestions:
Please send to Yair Altman (altmany at gmail dot com)

Comments and Ratings (13)

Unfortunately this does not seem to work on R2016a and (presumably) later versions of Matlab. The 'TC.xml' file no longer exists and appears to have been replaced by 'functionSignatures.json' files in the local directory of each function.


Will (view profile)

This works great. It would be nice if it would work on methods of classes as well, but I am guessing that is not possible with the way tab completion is currently implemented in MATLAB.


Will (view profile)

Todd Karin

Todd Karin (view profile)


Hi Yair,
this is really a great function. Currently I am searching for a solution to avoid a restart and reload TC.xml directly. Have you any hints or ideas to start from?


Thanks! Just another tiny issue that I came accross when using the new version. It seems that, under Linux, copyfile() may return status=1 even if the .bak file could not be created due to the lack of write permission in the relevant folder. At least in my Debian squeeze system I get status=1 but msg='Operation not permitted' and the .bak file is not created. Is this a MATLAB bug? So there is the possibility that the owner of TC.xml can now rewrite TC.xml (by changing permissions automatically) but fails to create a backup copy, as the toolbox/local directory is read-only by default. For the sake of safety I would test that the msg returned by copyfile is empty as well as checking that status is not zero.

Yair Altman

Yair Altman (view profile)

@German - I've uploaded a new version of this utility - please use the latest version. See the update notes below for more info.

Really helpful stuff. And the technical explanations at your blog are incredibly insightful. Thanks a lot for sharing this. I would suggest just two very minor modifications:

- Adding the MCOSPCG and MCOSCLASS options
- Under unix systems, automatically changing the permissions of the xml file before editing it. Usually you will be the owner of that file but by default its permissions are set to read-only. You could change the permissions back to read-only after the editing.


Thanks a lot, this is really helpful :)

Yair Altman

Yair Altman (view profile)

Yogesh - the tex warning is harmless. To remove it, simply modify 'tex' to 'non' in line #110.

The error itself is due to the fact that you cannot save the TC.bak file in your system for some reason (perhaps it is read-only?)

Y Mehta

I get the following error in 2010a

Warning: Unable to interpret TeX string "Save C:\Program Files\MATLAB\R2010a\toolbox\local\TC.bak?"
> In questdlg at 277
In tabcomplete at 112
??? Error using ==> tabcomplete at 117
Failed to create C:\Program Files\MATLAB\R2010a\toolbox\local\TC.bak:
Access is denied.

117 error('YMA:TabComplete:CreateBakup','Failed to create %s:\n%s',bakFilename,msg);


David (view profile)

Thanks for posting this great utility! Seeing your question dialog and looking through the code, I saw your use of the function "setpref." I didn't know about this very useful function, so thanks for that too!



Added MCOSPKG,MCOSCLASS (R2010a+), MESSAGEID (R2011b+) argTypes; warn when using extra vars in R2010a-R2011b; attempt to make TC.xml writeable before updating; fixed possible Matlab hang after answering the backup dialog window


Minor fix to msgbox in case of backup problem (per Yogesh's comment)

MATLAB Release
MATLAB 7.6 (R2008a)

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