Reimplements a helper the project already has, under the same or another name

Code that already exists: one of the ways AI coding agents bloat software, from lessloc's pattern catalog. lessloc gives every session the rule: take what is already in the codebase before new code.

What makes reimplementing a helper the project already has a bad practice?

The standards that call it a bad practice: DRY (Hunt & Thomas, The Pragmatic Programmer); Fowler, Refactoring: Duplicated Code; CWE-1041 Use of Redundant Code; Sonar S4144.

What does lessloc do about reimplementing a helper the project already has?

lessloc gives every session the rule: take what is already in the codebase before new code. Hints name existing code before the task and inside each subagent's prompt. lessloc catches it as copy, near-copy and similar-name.

• copy (tier 1): A block of dupLines code lines that also exists elsewhere, or a function with the same body as another under other names.
• near-copy (tier 2): A new function that is mostly the same code as an existing one.
• similar-name (tier 2): A new function whose name looks like an existing one's.

Related patterns

The other patterns in Code that already exists:

• Copying a rule another function owns: lessloc catches it as repeated-literal.
• Keeping old and new versions side by side: lessloc gives every session the rule: one implementation per rule.
• Rebuilding what the standard library or framework has: lessloc gives every session a rule against it and catches it as simpler and reinvented.
• Copy-pasted test cases instead of one parametrized test: lessloc catches it as copied-tests.
• A second library for a job an installed one already does: new-dependency names the library that is already installed.
• The same data shape in several layers (DTO, model, entity): copy catches identical type bodies.
• The same CSS declarations under another selector: lessloc catches it as style-copy.