home / skills / mhattingpete / claude-skills-marketplace / code-transfer
This skill transfers code between files with line precision, enabling fast extraction, insertion, and reorganization across projects.
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---
name: code-transfer
description: Transfer code between files with line-based precision. Use when users request copying code from one location to another, moving functions or classes between files, extracting code blocks, or inserting code at specific line numbers.
---
# Code Transfer
Transfer code between files with precise line-based control. **Dual-mode operation**: native tools (1-10 files) or execution mode (10+ files, 90% token savings).
## Operation Modes
### Basic Mode (Default)
Use Read, Edit, Bash scripts for 1-10 file operations. Works immediately, no setup required.
### Execution Mode (10+ files)
```python
from api.filesystem import batch_copy
from api.code_analysis import find_functions
functions = find_functions('app.py', pattern='handle_.*')
operations = [{
'source_file': 'app.py',
'start_line': f['start_line'],
'end_line': f['end_line'],
'target_file': 'handlers.py',
'target_line': -1
} for f in functions]
batch_copy(operations)
```
## When to Use
- "copy this code to [file]"
- "move [function/class] to [file]"
- "extract this to a new file"
- "insert at line [number]"
- "reorganize into separate files"
## Core Operations
### 1. Extract Source Code
```
Read(file_path="src/auth.py") # Full file
Read(file_path="src/auth.py", offset=10, limit=20) # Line range
Grep(pattern="def authenticate", -n=true, -A=10) # Find function
```
### 2. Insert at Specific Line
Use `line_insert.py` script for line-based insertion:
```bash
python3 skills/code-transfer/scripts/line_insert.py <file> <line_number> <code> [--backup]
```
**Examples:**
```bash
# Insert function at line 50
python3 skills/code-transfer/scripts/line_insert.py src/utils.py 50 "def helper():\n pass"
# Insert with backup
python3 skills/code-transfer/scripts/line_insert.py src/utils.py 50 "code" --backup
# Insert at beginning
python3 skills/code-transfer/scripts/line_insert.py src/new.py 1 "import os"
```
**When to use:**
- User specifies exact line number
- Inserting into new/empty files
- Inserting at beginning/end without context
### 3. Insert Relative to Content
Use **Edit** when insertion point is relative to existing code:
```
Edit(
file_path="src/utils.py",
old_string="def existing():\n pass",
new_string="def existing():\n pass\n\ndef new():\n return True"
)
```
## Workflow Examples
### Copy Function Between Files
1. Find: `Grep(pattern="def validate_user", -n=true, -A=20)`
2. Extract: `Read(file_path="auth.py", offset=45, limit=15)`
3. Check target: `Read(file_path="validators.py")`
4. Insert: Use `line_insert.py` or Edit based on context
### Extract Class to New File
1. Locate: `Grep(pattern="class DatabaseConnection", -n=true, -A=50)`
2. Extract: `Read(file_path="original.py", offset=100, limit=50)`
3. Create: `Write(file_path="database.py", content="<extracted>")`
4. Update imports: `Edit` in original file
5. Remove old class: `Edit` with replacement
### Insert at Specific Line
1. Validate: `Read(file_path="main.py", offset=20, limit=10)`
2. Insert: `python3 skills/code-transfer/scripts/line_insert.py main.py 25 "logger.info('...')" --backup`
3. Verify: `Read(file_path="main.py", offset=23, limit=5)`
### Reorganize Into Modules
1. Analyze: `Read(file_path="utils.py")`
2. Identify groups: `Grep(pattern="^def |^class ", -n=true)`
3. Extract each category: `Write` new files
4. Update original: Re-export or redirect
## Best Practices
**Planning:**
- Understand dependencies (imports, references)
- Identify exact start/end of code block
- Check target file structure
- Ensure necessary imports included
**Preservation:**
- Include docstrings and comments
- Transfer related functions together
- Update imports in both files
- Maintain formatting/indentation
**Validation:**
- Verify insertion placement
- Check syntax
- Test imports
- Suggest running tests
**Backups:**
- Use `--backup` for significant changes
- Critical file operations
- Large deletions
## Integration
- **code-refactor**: Refactor after transferring
- **test-fixing**: Run tests after reorganizing
- **feature-planning**: Plan large reorganizations
This skill transfers code between files with line-based precision, supporting both small direct edits and large, batched operations. It offers dual-mode operation: a Basic Mode for immediate 1–10 file edits and an Execution Mode for high-volume transfers with token-efficient batching. Use it when you need exact control over where code is copied, moved, or extracted.
The skill reads exact line ranges or searches for patterns to locate code blocks, then inserts or writes those blocks at specified line numbers or relative to existing content. For 1–10 files it uses read/edit/bash scripts and simple line-insert helpers; for 10+ files it switches to an execution API that batches operations to save tokens and speed execution. It also supports backups, content-aware edits, and follow-up updates like import fixes.
When should I use Execution Mode instead of Basic Mode?
Use Execution Mode for operations across 10 or more files or when you want token-efficient, batched transfers. Basic Mode is faster to start for 1–10 files and needs no setup.
How do I ensure imports and references remain valid after moving code?
Plan dependency changes first, transfer related functions together, update imports with targeted edits, and run tests to catch broken references.