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Rename a symbol across the repo in Perl with Atlas in 2026

Updated 11 min read

Renaming a function, class, or constant across an entire Perl repository in 2026 is a precise operation that Atlas handles by combining language server protocol (LSP) accuracy with robust text search and controlled editing. Atlas uses the `lsp` tool's `findReferences` to get the authoritative list of callsites from your Perl language server, ensuring type-aware changes. It then employs `grep` to locate non-code occurrences like strings, comments, and documentation, which are often missed by compiler-centric tools. Mechanical replacements are performed with the `edit` tool, which enforces unambiguous changes per file, preventing silent corruption. Finally, Atlas integrates with your Perl toolchain, allowing you to run `prove (Test2::V0)` for testing and `perltidy` for formatting, all within a permission-gated workflow.

How Atlas renames Perl symbols across a repository

Atlas renames Perl symbols by orchestrating three core tools: `lsp`, `grep`, and `edit`. This multi-faceted approach ensures that in 2026, every instance of a symbol, from a `sub` declaration in a `.pm` module to a string literal in a configuration file, is accurately identified and updated. The process begins with the language server for type-aware precision.

When you initiate a symbol rename in a Perl codebase with Atlas, the first step involves the `lsp` tool. Atlas invokes the `findReferences` operation on the target symbol, querying your local Perl language server. This provides an authoritative list of all code-level references, including function calls, class instantiations, and constant usages, across your `.pm` modules and scripts. This method is crucial for Perl, where dynamic features can make static analysis challenging, but a well-configured language server provides the necessary context. Following the `lsp` operation, Atlas uses its `grep` tool to search for the old symbol name. This step is vital for catching occurrences that the language server might overlook, such as the symbol name embedded in comments, documentation, log messages, or configuration files. For example, if you are renaming a function `_old_utility_sub` to `_new_utility_sub`, `grep` will find instances in a `README.md` file or a `config.json` that are not part of the Perl AST. This hybrid approach ensures comprehensive coverage. Finally, the `edit` tool performs the mechanical replacement. Atlas uses `replaceAll` for these operations, but with a critical safety mechanism: `edit` refuses ambiguous single replacements. If an unintended match occurs, Atlas will report an error rather than silently corrupting your code. This ensures that every change is intentional and verifiable, providing a robust safety net for refactoring Perl codebases, especially those with complex `@EXPORT` lists or `cpanfile` dependencies.

Perl-specific considerations for symbol renaming with Atlas

Renaming symbols in Perl requires an understanding of its unique ecosystem, including `cpanm` for dependencies and `Makefile.PL` or `cpanfile` for distribution metadata. Atlas is designed to operate within this context, reading your packages and `@EXPORT` lists to ensure comprehensive refactoring. In 2026, Atlas leverages these details for precise symbol identification.

Atlas is built to integrate direct with the Perl development environment. When you run Atlas in a distribution containing a `cpanfile` or `Makefile.PL`, it automatically reads your project's structure, including declared packages and the modules pulled in by `cpanm`. This understanding is critical for accurate symbol renaming, as Perl's module system and `@EXPORT` lists dictate how functions and variables are made available across different `.pm` files. For instance, if you are renaming a function that is part of an `@EXPORT` list in a module like `My::Module.pm`, Atlas's `lsp` tool will correctly identify all call sites in other modules that `use My::Module`. The `grep` tool will then ensure that any references to the old name in `perldoc` comments or example scripts are also updated. Atlas's ability to build its code index using AST declarations from tree-sitter, rather than blind line windows, provides a deeper, more accurate understanding of Perl code structure, which is essential for avoiding false positives or missed changes in a language known for its flexibility. Furthermore, Atlas's capability to connect to Model Context Protocol servers and expose their tools to the agent means it can leverage advanced Perl-specific language server features. This ensures that even complex Perl idioms, such as those involving `BEGIN` blocks or `AUTOLOAD` functions, are handled correctly during a rename operation, maintaining the integrity of your codebase.

Ensuring code quality: Testing and formatting after a Perl rename

After renaming a symbol in a Perl project, verifying functionality and maintaining code style are paramount. Atlas integrates directly with the Perl toolchain, allowing you to run `prove (Test2::V0)` to execute your test suite and `perltidy` to format changed files. This ensures that in 2026, your refactoring is both functionally correct and aesthetically consistent.

Once Atlas has applied the mechanical renames, the next critical step is to compile and test the Perl codebase. Atlas facilitates this by allowing you to execute arbitrary `bash` commands. You can instruct Atlas to run your test suite using the standard Perl test runner: `prove -lr t/`. This command will execute all `Test2::V0` cases located under your `t/` directory, providing immediate feedback on whether the refactoring has introduced any regressions. Atlas will present the TAP output from `prove` directly in your terminal, allowing you to review test results before committing any changes. Maintaining consistent code style is equally important. Atlas integrates with `perltidy`, the widely used Perl code formatter. After the rename and successful testing, you can have Atlas run `perltidy` on all the files it modified. This ensures that the diff generated by Atlas for your review will match your project's `.perltidyrc` configuration, preventing unnecessary style changes from cluttering the refactoring diff. This attention to detail helps maintain a clean `git` history and adheres to established Perl coding standards. Atlas's permission-gated tool calls mean that every execution of `prove` or `perltidy` is subject to your approval, providing full control over the refactoring process. This ensures that you, the Perl developer, remain in charge, with Atlas acting as an intelligent assistant that executes commands only with explicit permission.

Safety and review mechanisms for Perl refactoring with Atlas

Atlas prioritizes safety and transparency during Perl refactoring operations, offering multiple layers of review and control. Every file edit generates a unified diff for your approval, and Atlas drafts a plan in a read-only agent before executing any changes. This robust system ensures that in 2026, you have complete oversight over every symbol rename.

One of Atlas's core safety features for Perl refactoring is its comprehensive review process. Before any changes are written to your files, Atlas computes a unified diff for every proposed edit and surfaces it for your approval. This allows you to meticulously review exactly what will change, line by line, across all affected `.pm` modules, scripts, and configuration files. This visual confirmation is invaluable for catching any unintended modifications or ensuring that the new symbol name is applied correctly in all contexts. Furthermore, Atlas operates with a 'plan agent' that drafts a detailed refactoring plan in a read-only state. This plan outlines the steps Atlas intends to take, such as which files to modify and which tools (`lsp`, `grep`, `edit`, `bash`) it will use. You are prompted to approve this plan before Atlas switches to a 'build agent' to execute the changes. This two-stage process provides an additional layer of control, allowing you to understand and sanction the entire workflow before any code is touched. Atlas also integrates with `git`, reading branches, status, and diffs. It can stage and create commits on your behalf, streamlining the version control aspect of refactoring. If you need to roll back changes, Atlas snapshots file modifications as `git` patches, making it easy to revert edits. This comprehensive suite of safety and review mechanisms ensures that renaming a symbol in your Perl codebase with Atlas is a controlled, transparent, and reversible process, minimizing risk and maximizing developer confidence.

Handling edge cases: Strings, comments, and documentation in Perl

Renaming a Perl symbol often extends beyond code declarations to include occurrences in strings, comments, and documentation. Atlas addresses these edge cases by combining `lsp`'s precise code references with `grep`'s ability to find text patterns. This ensures that in 2026, your refactoring is complete, even for instances that are not part of the Perl Abstract Syntax Tree.

While the `lsp` tool provides an authoritative list of code references for Perl symbols, many instances of a symbol's name exist outside the strict confines of the type system. These include the symbol name used within string literals, embedded in comments, or appearing in `perldoc` documentation blocks. Atlas's workflow explicitly accounts for these edge cases by employing its `grep` tool. After the `lsp` tool identifies all code-level references, Atlas runs `grep` for the old symbol name across the entire repository. This sweep catches occurrences in places like `my $message = "Calling old_function...";` or `# TODO: Refactor old_function later`. It also finds instances in `README.md` files, `CHANGELOG` entries, or even custom configuration files that might reference the Perl symbol. The `grep` results are then presented, allowing Atlas to apply targeted `edit` operations. Crucially, the `edit` tool's `replaceAll` functionality is used for these mechanical changes. However, `edit` is designed to prevent accidental broad replacements. If a single occurrence must change, `edit` enforces uniqueness, throwing `Found multiple matches for oldString` unless you add specific context or explicitly opt into `replaceAll`. This prevents a generic `grep` match from inadvertently changing unrelated text. This meticulous approach ensures that every instance of the old symbol name, regardless of its context within your Perl project, is considered and updated, leading to a truly complete refactoring.

Step by step

  1. 01Initiate the rename by asking Atlas to run the `lsp` tool's `findReferences` operation on the Perl symbol you wish to rename. This will gather the authoritative callsite list from your language server, covering `.pm` modules and scripts.
  2. 02Next, instruct Atlas to run `grep` for the old symbol name across your repository. This step is crucial for catching occurrences outside the Perl type system, such as in strings, comments, `perldoc` documentation, or configuration files.
  3. 03Apply the mechanical renames using Atlas's `edit` tool with `replaceAll`. Atlas will present a unified diff for each file, and you will approve these changes. The `edit` tool enforces unambiguous replacements per file, preventing unintended matches.
  4. 04After the edits, ask Atlas to run your Perl test suite. Use the `bash` tool to execute `prove -lr t/`. Atlas will display the TAP output from `Test2::V0` for your review, ensuring no regressions were introduced by the rename.
  5. 05To maintain code style, have Atlas run `perltidy` on all the changed files. This ensures that the diff matches your project's `.perltidyrc` and keeps your Perl codebase consistently formatted.
  6. 06Perform a final verification by asking Atlas to run `grep` once more for the old symbol name. This confirms that zero remaining hits exist across your entire Perl repository, including `cpanfile` or `Makefile.PL` related files.
  7. 07Review the final unified diffs presented by Atlas. Once satisfied, allow Atlas to stage and create a `git` commit on your behalf, completing the symbol rename in your Perl project.

Frequently asked questions

How does Atlas handle Perl modules with `@EXPORT` lists during a rename?
Atlas leverages its `lsp` tool, which understands Perl's module system and `@EXPORT` lists. When you rename a symbol, `lsp` accurately identifies all modules that `use` or `require` the affected module and updates the references accordingly, ensuring your Perl code remains functional.
Can Atlas rename a Perl constant defined in a `use constant` declaration?
Yes, Atlas can rename constants defined with `use constant`. The `lsp` tool will identify all usages of the constant across your Perl codebase, and the `edit` tool will apply the new name. `grep` will also catch any non-code references to the constant name.
What if the old Perl symbol name appears in a `cpanfile` or `Makefile.PL`?
Atlas's `grep` tool is designed to catch occurrences of the old symbol name in files like `cpanfile` or `Makefile.PL`, as these are outside the scope of the language server's code analysis. You can then use the `edit` tool to apply the necessary changes, ensuring a complete rename across your Perl distribution.
How does Atlas ensure my Perl tests pass after a symbol rename?
After performing the renames, Atlas allows you to run `bash` commands, specifically `prove -lr t/`. This executes your `Test2::V0` test suite. Atlas displays the TAP output, enabling you to verify that all tests pass before committing the changes, ensuring the functional integrity of your Perl application.
Does Atlas integrate with `perltidy` for formatting Perl code?
Yes, Atlas integrates with `perltidy`. After the rename, you can instruct Atlas to run `perltidy` on the modified files. This ensures that the code style remains consistent with your `.perltidyrc` configuration, and the resulting diffs are clean and focused on the refactoring.
What safety measures does Atlas have to prevent accidental changes in Perl code?
Atlas employs several safety measures: it drafts a read-only plan for your approval, computes a unified diff for every file edit before writing, and uses permission-gated tool calls. The `edit` tool also refuses ambiguous single replacements, preventing silent corruption in your Perl codebase.

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