How to Use the Command 'mh_lint' (with examples)

The ‘mh_lint’ command is a powerful tool designed to locate potential bugs in MATLAB or Octave code. While it is important to note that this tool is neither sound nor complete, it serves as a valuable asset for developers looking to enhance the quality of their code by identifying possible errors or inefficiencies. More information can be found at Miss Hit .

Use Case 1: Check the Current Directory

Code:

mh_lint

Motivation: When working on MATLAB or Octave projects, developers often accumulate numerous scripts and functions in a single directory. Using ‘mh_lint’ to check the current directory without specifying a path allows you to conduct a quick, broad sweep to identify potential issues across all relevant files. This capability is particularly useful for maintaining a high standard of code quality and consistency across your project.

Explanation: The command mh_lint without any additional arguments is a straightforward invocation, signaling the tool to inspect all MATLAB files located in the current working directory. It does not traverse into subdirectories, focusing solely on the files immediately present.

Example Output:

File: script1.m
Line 15: Possible use of uninitialized variable 'x'
Line 22: Function 'foo' might be unused

Use Case 2: Check a Specific Directory Recursively

Code:

mh_lint path/to/directory

Motivation: Projects can often span multiple subdirectories, especially larger, more complex ones. By specifying a directory path, ‘mh_lint’ can conduct a thorough analysis of every file in that directory, inclusive of all subdirectories. This recursive feature is crucial when managing large codebases, ensuring that no potential bug escapes unnoticed regardless of file location.

Explanation: In this command, mh_lint path/to/directory, the specified path tells the tool exactly where to search for MATLAB scripts and functions. It extends its analysis to every subdirectory within the given path, thanks to the recursive nature of the command.

Example Output:

Checking directory: path/to/directory
File: subdir1/function1.m
Line 8: Unused variable 'y'

File: subdir2/script2.m
Line 19: Function 'bar' re-declared but never used

Use Case 3: Check a MATLAB File

Code:

mh_lint path/to/file.m

Motivation: Individually written MATLAB files often serve specific purposes within broader projects or are standalone calculations and simulations. Checking a single file using ‘mh_lint’ can help in identifying bugs in targeted scripts, allowing a focused approach to debugging, refining specific portions of code without delving into other files unnecessarily. This targeted inspection can be particularly beneficial during the development process of new features or algorithms.

Explanation: When executing mh_lint path/to/file.m, the command is instructed to focus its linting process on the specified MATLAB file. This method is beneficial for developers seeking to resolve issues within a distinct piece of code or before integrating the file into a larger codebase.

Example Output:

File: path/to/file.m
Line 3: 'a' variable assigned but not used
Line 10: Mismatched end in function definition

Use Case 4: Check an Octave File

Code:

mh_lint --octave path/to/file.m

Motivation: Octave, a widely used alternative to MATLAB owing to its open-source nature, features subtle syntactic and functional differences. By using the --octave flag with ‘mh_lint’, developers can ensure that their Octave scripts are free from bugs specifically related to the Octave environment. This capability is indispensable for those who frequently switch between MATLAB and Octave or those who develop open-source projects intended for Octave users.

Explanation: The command mh_lint --octave path/to/file.m integrates an additional flag, --octave, which customizes the linting process to accommodate Octave-specific conventions. This specification ensures that checks are optimally aligned with Octave’s operational context, reducing false positives that might arise from MATLAB-oriented rules.

Example Output:

File: path/to/file.m
Line 5: Potential issue with matrix indexing
Line 12: Function 'baz' might cause dimensional errors in Octave

Conclusion:

The ‘mh_lint’ command offers a versatile approach to enhancing code integrity in MATLAB and Octave environments. By enabling thorough, recursive checks of directories and pinpoint examinations of individual files, it proves invaluable in maintaining a higher quality of programming practices. Whether ensuring consistency across an extensive codebase or refining a single script, ‘mh_lint’ is an essential tool for developers aiming to mitigate bugs efficiently.