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Rule request: Avoid using the Assignment by Addition Operator (`+=`) to build a string

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#1,935 1 comment 0 reactions 0 assignees View on GitHub

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Assessment

Difficulty
4/5
Estimated time
3-5 days
Newbie friendliness
38/100
Issue type
Feature
Clarity
Mostly clear
Activity status
Stale
Tech stack
csharp, powershell
Domain
tooling

Research direction

Start by reviewing the linked AvoidPlusEqualsToBuildStrings prototype and the issue's references on PowerShell string addition. Then inspect PSScriptAnalyzer's existing rule patterns and tests. Done means a rule identifies += usage for building strings and reports it consistently with the project's analyzer conventions.

Written by the indexing model from the issue text.

Description

Issue - Discussion

Summary of the new feature

Strings are immutable. Each addition to the string actually creates a new string big enough to hold the contents of both the left and right operands, then copies the elements of both operands into the new string. For small strings, this overhead may not matter. For large strings, this can affect performance and memory consumption.
This will create more awareness of the possible performance impact of using the Assignment by Addition Operator (+= ), see also:

Proposed technical implementation details (optional)

See (PowerShell based) prototype AvoidPlusEqualsToBuildStrings at: https://github.com/iRon7/PSRules

What is the latest version of PSScriptAnalyzer at the point of writing

1.21.0

Dominant language
C#
Stars
2.2k
Forks
415
Avg merge
13h 1m
Merged PRs (30d)
2

Contributor guide

Open the contributing guide

First steps

  1. Read the whole issue, then the project's contributing guide.
  2. Comment on the issue to say you are picking it up — it saves two people doing the same work.
  3. Fork the repository and make your change on a branch.
  4. Open a pull request that references the issue number.

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