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# Diff Operations
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Comprehensive diff functionality for comparing commits, trees, and working directory state. Supports unified diff generation, patch creation, and change detection.
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## Capabilities
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```python { .api }
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class Diff:
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    def __init__(self, repo: "Repo", a_rawpath: bytes, b_rawpath: bytes, a_blob_id: str, b_blob_id: str, a_mode: int, b_mode: int, new_file: bool, deleted_file: bool, copied_file: bool, raw_rename_from: str, raw_rename_to: str, diff: str, change_type: str):
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        """Initialize diff."""
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    @property
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    def a_path(self) -> str:
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        """Path in A side."""
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    @property
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    def b_path(self) -> str:
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        """Path in B side."""
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    @property
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    def change_type(self) -> str:
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        """Change type (A/D/M/R/C/T/U)."""
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    @property
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    def diff(self) -> str:
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        """Unified diff text."""
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class DiffIndex(list):
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    def iter_change_type(self, change_type: str) -> Iterator["Diff"]:
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        """Iterate diffs of specific change type."""
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class Diffable:
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    def diff(self, other: Union["Diffable", str, None] = None, paths: Union[str, list] = None, create_patch: bool = False, **kwargs) -> "DiffIndex":
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        """Create diff."""
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NULL_TREE = object()  # Represents empty tree
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INDEX = object()  # Represents index state
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class DiffConstants:
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    """Constants for diff operations."""
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```
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## Usage Examples
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```python
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from git import Repo
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repo = Repo('/path/to/repo')
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# Compare commits
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commit1 = repo.commit('HEAD~1')
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commit2 = repo.commit('HEAD')
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diffs = commit1.diff(commit2)
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for diff in diffs:
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    print(f"{diff.change_type}: {diff.a_path} -> {diff.b_path}")
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    if diff.diff:
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        print(diff.diff)
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# Compare working tree to index
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index_diffs = repo.index.diff(None)
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# Compare specific files
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file_diffs = commit1.diff(commit2, paths=['README.md'])
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```