Autocomplete of filenames for function input params

When using matlab functions such as "load" or "save" you can double-tab to autocomplete filenames that are in the path. However, when I have written my own functions that take filename strings as input this feature is not available (Which is reasonable since all functions shouldn't assume filename input).

I wonder if it is possible to somehow "hint" your own functions that they should try to autocomplete input parameters by searching over files in your matlab path.

[Luke Winslow]

Wow, this is *exactly* the same question I had. I haven't been able to figure it out, but I did look into existing matlab functions, and it offers no help.

For example, the 'importdata' function auto-completes file names, but it doesn't seem to do anything special to the input. It immediately puts the first argument into a variable called FileName, but I tried that and it doesn't seem to make a difference. I'd really like to know the answer to this as the auto-complete is super useful.

Answer 1

[Nicholas Mati]

At some point between R2015a and R2016b, Matlab switched from using the TC.xml file to a more flexible and readable JSON implementation. Tab-completion information is now stored in a functionSignatures.json file located in the same directory as the relevant function's m-file. This also means you no longer have to hack Matlab root files in order to enjoy tab completion.

The function signatures file has the general form:

{
"FunctionName1":
{
  "key1":"val1",
  "key2":"val2",
  "keyn":"valn"
},
"FunctionName2":
{
  "key1":"val1",
  "key2":"val2",
  "keyn":"valn"
}
}

A number of keys are supported including "platform", "setsAns", "inputs", and "outputs", although inputs and outputs are by far the most common. Both of these keys take an array of objects that describe the input / output variable(s) and how to tab complete them.

The objects typically take one of the following forms:

{"name":"variable_name", "kind":"kind_option", "type":"string_or_array_of_type"}

{"mutuallyExclusiveGroup":
  [
    ...
  ]
}

{"name":"varargin", "kind":"optional", "multiplicity":"append"}

The value for "kind" can include (but may not be limited to) "required", "optional", and "namevalue". The value for "type" can be a string such as "filepath" for tab completion of files, or a more complicated JSON array. Examples can be found in matlabroot/toolbox/matlab. It appears that matlabroot/toolbox/matlab/imagesci/functionSignatures.json has a particularly rich set of examples on how to do auto-completion. Here are entries for two functions that I cherry-picked from that file:

...
"h5read":
{
  "inputs":
  [
    {"name":"filename", "kind":"required", "type":"filepath"},
    {"name":"varargin", "kind":"optional", "multiplicity":"append"}
  ]
},
...
"imread":
{
  "inputs":
  [
    {"mutuallyExclusiveGroup":
      [
        {"name":"filename", "kind":"required", "type":[["filepath=*.cur,*.ico,*.gif,*.hdf"], ["matlabpath=*.cur,*.ico,*.gif,*.hdf"]]},
        [
          {"name":"filename", "kind":"required", "type":[["char"], ["filepath"]]},
          {"name":"fmt", "kind":"required", "type":["char", "choices={'cur','ico','gif','hdf'}"]}
        ]
      ]
    },
    {"name":"idx", "kind":"optional", "type":["numeric", "vector", ">=1"]}
  ],
  "outputs":
  [
    {"name":"A", "type":[["numeric", "2d"], ["numeric", "3d"]]}
  ]
},
...

[Yair Altman]

A detailed explanation of the mechanism was posted here: http://undocumentedmatlab.com/blog/user-defined-tab-completions-take-2

[Walter Roberson]

Official documentation of this is at https://www.mathworks.com/help/matlab/matlab_prog/customize-code-suggestions-and-completions.html

[Yair Altman]

Thanks Walter - I added the official link to my blog post. It's about time they made it documented/supported - it's been around for a long time...

Answer 2

[Jan]

See Yair's article about tab-completion: Undocumented:Tab-Completeion

There you find instructions for editing:

 edit(fullfile(matlabroot,'toolbox/local/TC.xml'))

[Walter Roberson]

Neato!

[Miro]

Worked on 2011a, with the minor mod that TC.xml was write-protected by default

[Tyvaughn Holness]

Worked on 2015a! The .json method did not

[Yair Altman]

As Nicholas Mati answered below, Matlab switched from using TC.xml to the JSON mechanism around 2015-2016. The original question was made in 2011; my article about the undocumented TC.xml mechanism was posted in 2010. This worked well until 2015-ish, but for newer Matlab releases you need to use the JSON mechanism. Nothing lasts forever...

Answer 3

[Walter Roberson]

As of 2010a this was not possible at the user level. I have not heard any evidence that the situation has changed since.

Answer 4

[AMM]

Is there a way to use wildcards other than asterisks for filenames in a JSON block like

{"name":"filename", "kind":"required", "type":[["file=*.txt,*.asc,*.*n"], ["folder"], ["char"]]}

I ask because I want to match files with suffixes of the form filename.06n, where the two characters preceding the final "n" can be any digits, but not anything else. In UNIX I would use something like

file=*.txt,*.asc,*.*[0-9][0-9]n

... but that doesn't work at all in my functionSignatures.json.

Answer 5

[Tracy Fulghum]

A user hack is to use the ls function as a wrapper around your filename argument, and exploit the autocomplete of the ls function, as in

myFunction(ls('aFileName<tab>'), ...)
    

The ls function will autocomplete whatever file name you're looking for and return a string listing it.

[Matt J]

This unfortunately only works if aFilename<tab> is located in the current folder. Also, it doesn't appear to support command syntax:

>> myFunction ls('aFileName<tab>')

[Brian]

I believe the limitation on current folder can be addressed by wrapping with

fullfile() 

instead of

ls() 

This should allow tab completion from anywhare on the filesystem and return the path and file exactly as tab-completed.

However, I don't think this addresses the limitation regarding command syntax.