164e19962b
Co-authored-by: Claire W <78226508+crwaters16@users.noreply.github.com> Co-authored-by: Anne-Marie <102995847+am-stead@users.noreply.github.com> Co-authored-by: Jules <19994093+jules-p@users.noreply.github.com> Co-authored-by: Jules Porter <jules-p@users.noreply.github.com> Co-authored-by: hubwriter <hubwriter@github.com> Co-authored-by: Robert Sese <734194+rsese@users.noreply.github.com>
125 lines
3.9 KiB
Markdown
125 lines
3.9 KiB
Markdown
---
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title: Explaining legacy code
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shortTitle: Explain legacy code
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intro: '{% data variables.copilot.copilot_chat_short %} can help with explaining unfamiliar code.'
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redirect_from:
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- /copilot/example-prompts-for-github-copilot-chat/documenting-code/explaining-legacy-code
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- /copilot/copilot-chat-cookbook/documenting-code/explaining-legacy-code
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- /copilot/tutorials/copilot-chat-cookbook/documenting-code/explaining-legacy-code
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- /copilot/tutorials/copilot-chat-cookbook/documenting-code/explain-legacy-code
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versions:
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feature: copilot
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category:
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- Documenting code
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- Author and optimize with Copilot
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complexity:
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- Simple
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octicon: book
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topics:
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- Copilot
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contentType: tutorials
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---
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One of the biggest challenges with legacy code is helping developers understand it who aren't familiar with the languages or frameworks. With {% data variables.copilot.copilot_chat_short %}, you can explain the background you have and ask for an explanation.
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## Example scenario
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Consider the following COBOL code. If you're a Python developer (as an example), you might not be familiar with COBOL, so you could ask {% data variables.copilot.copilot_chat_short %} to explain the code to you.
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```text id=cobol-insert-record
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IDENTIFICATION DIVISION.
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PROGRAM-ID. INSERT-RECORD.
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ENVIRONMENT DIVISION.
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DATA DIVISION.
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WORKING-STORAGE SECTION.
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01 WS-STATUS-FLAGS.
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05 WS-DB-STATUS PIC X(2).
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88 WS-SUCCESS VALUE "00".
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05 WS-SQLCODE PIC S9(9) COMP.
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05 WS-ERROR-MSG PIC X(50).
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LINKAGE SECTION.
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01 LS-PARAMETERS.
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05 LS-PERSON-RECORD.
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10 PERSON-ID PIC 9(6).
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10 PERSON-NAME PIC X(50).
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10 PERSON-AGE PIC 9(3).
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05 LS-RESULT PIC X.
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88 SUCCESS VALUE 'T'.
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88 FAILED VALUE 'F'.
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PROCEDURE DIVISION USING LS-PARAMETERS.
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PERFORM INSERT-AND-VALIDATE
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GOBACK
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.
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INSERT-AND-VALIDATE.
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EXEC SQL
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INSERT INTO persons (id, name, age)
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VALUES (:PERSON-ID, :PERSON-NAME, :PERSON-AGE)
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END-EXEC
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IF SQLCODE = 0
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EXEC SQL COMMIT END-EXEC
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SET SUCCESS TO TRUE
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ELSE
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EXEC SQL ROLLBACK END-EXEC
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SET FAILED TO TRUE
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STRING "DB Error: " SQLCODE
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DELIMITED BY SIZE
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INTO WS-ERROR-MSG
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DISPLAY WS-ERROR-MSG
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END-IF
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.
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```
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## Example prompt
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You can ask for an explanation of the COBOL code from the point of view of a Python developer.
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```copilot copy prompt ref=cobol-insert-record
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I'm a Python developer. Help me better understand this code. Please provide analogies.
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```
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## Example response
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{% data reusables.copilot.example-prompts.response-is-an-example %}
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{% data variables.product.prodname_copilot_short %} provides a high-level overview of the code, before walking through the various operations and explaining them in a way that Python developers can understand. It uses analogies to make the explanation more accessible. The response might start with the following:
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```text
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Let me explain this COBOL code using Python analogies:
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High-Level Overview
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This is similar to a Python function that inserts a person's record into a database with error handling.
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```
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```python
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# In Python, the COBOL divisions would be like:
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# IDENTIFICATION DIVISION = module/file name
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# PROGRAM-ID = function name
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def insert_record():
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pass
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# DATA DIVISION would be like declaring these variables:
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class WorkingStorage:
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db_status = "" # WS-DB-STATUS
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sqlcode = 0 # WS-SQLCODE
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error_msg = "" # WS-ERROR-MSG
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# LINKAGE SECTION is like function parameters
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class PersonRecord:
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def __init__(self, person_id: int, person_name: str, person_age: int):
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self.person_id = person_id # PERSON-ID
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self.person_name = person_name # PERSON-NAME
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self.person_age = person_age # PERSON-AGE
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self.success = False # LS-RESULT
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```
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## Further reading
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{% data reusables.copilot.example-prompts.further-reading-items %}
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