Avoid manual string trimming

Metadata

ID: go-best-practices/manual-string-trimming

Language: Go

Severity: Warning

Category: Best Practices

Description

In Go, the strings.TrimPrefix() function provides a more idiomatic and efficient way to remove a prefix from a string compared to using strings.HasPrefix() and slicing the string manually.

Here’s why you should use strings.TrimPrefix() instead of the manual slicing approach:

  1. Readability: strings.TrimPrefix(str, prefix) conveys the intention of removing the specified prefix from str more clearly than using strings.HasPrefix() and slicing str. It’s a self-explanatory function that makes the code more readable and easier to understand.
  2. Simplicity: By using strings.TrimPrefix(), you eliminate the need for manual slicing and calculating the length of the prefix. It simplifies your code and reduces the chances of introducing errors.
  3. Performance: strings.TrimPrefix() is implemented with optimal string manipulation techniques, making it more performant than manually slicing the string. It avoids creating unnecessary substrings, resulting in better efficiency when dealing with large strings.

For example, consider the following code snippets:

1
2
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if strings.HasPrefix(str, prefix) {
    str = str[len(prefix):]
}
str = strings.TrimPrefix(str, prefix)

Both snippets remove the prefix from the string if it exists. However, the second snippet using strings.TrimPrefix() is preferred for its simplicity, readability, and potential performance benefits.

By using strings.TrimPrefix() instead of the manual slicing approach, you can write cleaner and more efficient code that adheres to Go’s idiomatic principles.

Non-Compliant Code Examples

func main() {
    if strings.HasPrefix(str, prefix) {
        str = str[len(prefix):]
        str2 := str[len(prefix):]
    }
}

Compliant Code Examples

func main() {
    strings.TrimPrefix(str, prefix)
}