Developing cmake2graph

A Journey into CMake Dependency Visualization

As software projects grow larger, understanding dependencies between components becomes increasingly challenging. This is especially true for C++ projects using CMake, where target dependencies can quickly become complex. This led me to develop cmake2graph, a tool that visualizes CMake target dependencies as directed graphs.

The Problem

Working on large C++ codebases, I often encountered these challenges:

• Difficulty understanding dependency relationships
• Circular dependencies causing build issues
• Complex CMake files with unclear target relationships
• Hard to spot unnecessary dependencies

The Solution: cmake2graph

cmake2graph is a Python tool that:

1. Parses CMake files recursively
2. Extracts target dependencies
3. Builds a directed graph
4. Visualizes the relationships
5. Provides filtering options

Here's a simple example:

cmake2graph /path/to/project --output deps.png

Technical Implementation

The tool uses several key technologies:

• NetworkX: For graph creation and manipulation
• Matplotlib: For visualization
• CMake Parser: Custom implementation to extract dependencies

Key Features

• Recursive Parsing: Handles nested CMake files
• Dependency Filtering: Focus on specific targets
• Depth Control: Limit dependency chain depth
• External Library Filtering: Focus on project-specific targets
• Multiple Output Formats: Support for PNG, SVG, PDF

Lessons Learned

1. CMake Complexity: CMake's flexibility makes parsing challenging
2. Graph Layout: Finding the right balance between aesthetics and clarity
3. Performance: Handling large projects requires optimization
4. User Experience: Balancing features vs. simplicity

Future Development

Several exciting possibilities lie ahead:

1. Automatic Link Error Resolution

Currently planning to add features that:

• Analyze linking errors
• Suggest missing dependencies
• Automatically fix common linking issues

# Before: Link error
target_link_libraries(app core)

# After: Automatically fixed
target_link_libraries(app 
    PRIVATE
        core
        missing_dependency
)

2. CMake File Cleanup

Future versions could:

• Detect unused targets
• Remove redundant dependencies
• Standardize CMake syntax
• Enforce modern CMake practices

3. Dependency Analysis

Planning to add:

• Cycle detection and breaking
• Dependency impact analysis
• Build time optimization suggestions
• Target visibility recommendations

4. Integration Features

Looking to integrate with:

• IDE plugins
• CI/CD pipelines
• Build systems
• Static analyzers

Contributing

The project is open source and welcomes contributions. Key areas where help is needed:

• CMake parsing improvements
• Graph visualization enhancements
• Documentation
• Test coverage
• New feature implementation

Conclusion

cmake2graph started as a simple visualization tool but has grown into a platform for CMake dependency management. While it currently serves its basic purpose well, the potential for growth is significant.

The future roadmap focuses on making C++ dependency management more maintainable, visual, and automated. Whether you're managing a small project or a large codebase, understanding and optimizing dependencies is crucial for maintainable software.

Links

• GitHub Repository
• PyPI Package

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