copybook

1.0.16 verified Fri May 01 auth: no python

A Python library for parsing COBOL copybooks (data definition records). Current version 1.0.16. Development appears infrequent with no recent releases.

pip install copybook

Common errors

error AttributeError: module 'copybook' has no attribute 'Copybook' ↓

cause Trying to import Copybook directly without from syntax.

fix

Use 'from copybook import Copybook'.

error ParseError: Unexpected token ↓

cause Copybook contains unsupported COBOL constructs like OCCURS or REDEFINES.

fix

Simplify the copybook to only elementary items with PIC clauses. The library does not fully support complex COBOL.

Warnings

gotcha The parse method does not accept file paths; you must read the copybook file yourself and pass the content as a string. ↓

fix Use open('copybook.cbl').read() to get the content, then pass it to parse.

gotcha Copybook layout indices are 1-based, not 0-based. ↓

fix When using layout offsets, remember that the first byte is 1. Adjust if your downstream expects 0-based.

Imports

Copybook
wrong
```
import Copybook
```
correct
```
from copybook import Copybook
```
Copybook is a class, not a module. Using import Copybook will fail.
CopybookError
wrong
```
from copybook.errors import CopybookError
```
correct
```
from copybook import CopybookError
```
CopybookError is defined in __init__.py, not in a submodule.

Quickstart

Parse a COBOL copybook string and get field positions.

from copybook import Copybook

cb = Copybook('')
cb.parse(
    struct="
        01 RECORD.
           05 NAME    PIC X(30).
           05 AGE     PIC 9(3).
    "
)
print(cb.layout)
# Example output: {'NAME': (1, 30), 'AGE': (31, 33)}